纳米体系结构相变及物性的分子动力学模拟
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摘要
本文通过使用分子动力学方法研究了纳米材料多壁碳纳米管和硒化镉团簇在外压下的结构相变行为，以及基于碳纳米管基础上的储氢容器。主要研究内容可以概括为以下几部分：
第一，研究了外加压强下(10，10)@(15，15)，(9，9)@(14，14)，(8，8)@(13，13)，(7，7)@(12，12)及(6，6)@(11，11)五种公度匹配的扶手椅型双壁碳纳米管的结构相交。我们发现在一定压强下，这些碳纳米管都会发生管口截面从圆形转变到椭圆型的结构相变，这个相变压强主要由内管的大小决定。同时我们的计算结果表明碳管键长在相变后会突然变长，我们采用了一个简单的弹性模型来解释这一物理现象。
第二，研究了多壁碳纳米管在外压下的径向压力传递。结果表明外管对内管起到一个保护作用，使内管感受到的压强远远小于外压。我们发现径向压力传递系数主要由碳纳米管的大小及管间的结构匹配决定。同时我们提出了一个测量多壁碳纳米管径向压力传递系数的实验方法。
第三，研究了碳纳米管的抗内压性能，并在此基础上设计了一种纳米储氢容器。计算结果表明在2.5GPa的压强下这种容器的储氢效率可以达到7.7％。
第四，我们使用等压分子动力学的方法研究了硒化镉团簇在外压下的结构相变。我们发现硒化镉团簇的结构相变与其自身的大小及形状密切相关。计算结果表明球形纳米团簇的相变压强是随团簇的增大而逐渐减小的。在所有研究的多面体团簇相变后都是形成无缺陷的石盐结构，而球形团簇相变后的结构都是多晶界的。
另外在论文的第一章里简要介绍了碳纳米管材料的发现历史及一般性质，硒化镉团簇的研究背景。在第二章中对本论文所使用的分子动力学力方法作了介绍，包括该方法的基本概念、原子势函数以及不同的等温及等压分子动力学方法。
In this thesis we have studied the pressure-induced structure transition of multiwalled carbon nanotube and CdSe nanocrystal by using constant pressure molecular dynamics simulations. And we have designed a nanocontainer for the storage of hydrogen based on the carbon nanotube.
First, we have studied the structure of isolated DWCNTs under external pressure. We find that pressure-induced structure transition takes place in all the studied DWCNTs. The critical transition pressure is strongly dependent on the radius of the inner tube. The bond length of the carbon nanotube would increase after phase transition, and we use a elastic model to explain this physics phenomenon.
Second, the radial pressure transmission behavior of MWCNTs is studied. It is found that the response pressure of inner tube is much lower than the external pressure before structural transition happens. The pressure transmission efficiency increases with tube radius. Meanwhile the pressure transmission efficiency also depends upon morphology combination of MWCNTs. With the same size, the pressure transmission efficiency of commensurate MWCNTs is higher than that of incommensurate ones. Based on the simulation results, we propose an experimental method to determine the pressure transmission efficiency of MWCNTs.
Third, we have studied the possibility of carbon nanotube acting as high pressure container. Based on the results, we designed a nano-container for the storage of hydrogen. At 2.5 GPa, the storage weight ratio of the container approaches a promising 7.7%.
Fourth, the structural transformation of CdSe nanocrystals under hydrostatic pressure is studied. We have found the structural transformation of CdSe nanocrystal is highly affected by the size and shape. The results show that the pressure for WZ to RS structural transformation of spherical nanocrystal decreases with nanocrystal size, while it seems to increase for facet one. For all spherical nanocrystals, the final structures have nano scale grain boundaries. All the faceted ones undergo uniform deformation, the transformed RS structure is of single domain nanocrystal.
第一，研究了外加压强下(10，10)@(15，15)，(9，9)@(14，14)，(8，8)@(13，13)，(7，7)@(12，12)及(6，6)@(11，11)五种公度匹配的扶手椅型双壁碳纳米管的结构相交。我们发现在一定压强下，这些碳纳米管都会发生管口截面从圆形转变到椭圆型的结构相变，这个相变压强主要由内管的大小决定。同时我们的计算结果表明碳管键长在相变后会突然变长，我们采用了一个简单的弹性模型来解释这一物理现象。
第二，研究了多壁碳纳米管在外压下的径向压力传递。结果表明外管对内管起到一个保护作用，使内管感受到的压强远远小于外压。我们发现径向压力传递系数主要由碳纳米管的大小及管间的结构匹配决定。同时我们提出了一个测量多壁碳纳米管径向压力传递系数的实验方法。
第三，研究了碳纳米管的抗内压性能，并在此基础上设计了一种纳米储氢容器。计算结果表明在2.5GPa的压强下这种容器的储氢效率可以达到7.7％。
第四，我们使用等压分子动力学的方法研究了硒化镉团簇在外压下的结构相变。我们发现硒化镉团簇的结构相变与其自身的大小及形状密切相关。计算结果表明球形纳米团簇的相变压强是随团簇的增大而逐渐减小的。在所有研究的多面体团簇相变后都是形成无缺陷的石盐结构，而球形团簇相变后的结构都是多晶界的。
另外在论文的第一章里简要介绍了碳纳米管材料的发现历史及一般性质，硒化镉团簇的研究背景。在第二章中对本论文所使用的分子动力学力方法作了介绍，包括该方法的基本概念、原子势函数以及不同的等温及等压分子动力学方法。
In this thesis we have studied the pressure-induced structure transition of multiwalled carbon nanotube and CdSe nanocrystal by using constant pressure molecular dynamics simulations. And we have designed a nanocontainer for the storage of hydrogen based on the carbon nanotube.
First, we have studied the structure of isolated DWCNTs under external pressure. We find that pressure-induced structure transition takes place in all the studied DWCNTs. The critical transition pressure is strongly dependent on the radius of the inner tube. The bond length of the carbon nanotube would increase after phase transition, and we use a elastic model to explain this physics phenomenon.
Second, the radial pressure transmission behavior of MWCNTs is studied. It is found that the response pressure of inner tube is much lower than the external pressure before structural transition happens. The pressure transmission efficiency increases with tube radius. Meanwhile the pressure transmission efficiency also depends upon morphology combination of MWCNTs. With the same size, the pressure transmission efficiency of commensurate MWCNTs is higher than that of incommensurate ones. Based on the simulation results, we propose an experimental method to determine the pressure transmission efficiency of MWCNTs.
Third, we have studied the possibility of carbon nanotube acting as high pressure container. Based on the results, we designed a nano-container for the storage of hydrogen. At 2.5 GPa, the storage weight ratio of the container approaches a promising 7.7%.
Fourth, the structural transformation of CdSe nanocrystals under hydrostatic pressure is studied. We have found the structural transformation of CdSe nanocrystal is highly affected by the size and shape. The results show that the pressure for WZ to RS structural transformation of spherical nanocrystal decreases with nanocrystal size, while it seems to increase for facet one. For all spherical nanocrystals, the final structures have nano scale grain boundaries. All the faceted ones undergo uniform deformation, the transformed RS structure is of single domain nanocrystal.
引文
[1] H. W. Kroto, J. R. Heath, S. C. O' Brien, R. F. Curl, and R. E. Smalley. C60: Buckminsterfullerene. Nature, 318: 162-163, 1985.
[2] S. Iijima. Helical microtubules of graphitic carbon. Nature, 354: 56-58, 1991.
[3] T. W. Ebbesen, and P. M. Ajayan. Large-scale synthesis of carbon nanotubes. Nature, 358: 6383-6385, 1992.
[4] S. Iijima and T. Ichihashi. Single-shell carbon nanotubes of 1-nm diameter. Nature, 363: 603-605, 1993.
[5] D. S. Bethune, C. H. Klang, M. S. de Vries, G. Gorman, R. Savoy, J. Vazquez, and R. Beyers. Cobalt-catalysed growth of carbon nanotubes with singleatomic- layer walls. Nature, 363: 605-607, 1993.
[6] A. Thess, et al., Crystalline Ropes of Metallic Carbon Nanotubes. Science, 273: 483-487, 1996.
[7] C. Liu, Y. Y. Fan, M. Liu, H. T. Cong, H. M. Cheng, and M. S. Dresselhaus. Hydrogen Storage in Single-Walled Carbon Nanotubes at Room Temperature. Science, 286: 1127-1129, 1999.
[8] C. Liu, H. T. Cong, F. Li, P. H. Tan, H. M. Cheng, K. Lug and B. L. Zhou. Semi-continuous synthesis of single-walled carbon nanotubes by a hydrogen arc discharge method. Carbon, 37: 1865-1868, 1999.
[9] J. Tersoff, and R. S. Ruoff. Structural Properties of a Carbon-Nanotube Crystal. Phys. Rev. Lett. , 73: 676-679, 1994.
[10] Gao Gh, Cagin T, and Goddard WA. Energetics, structure, mechanical and vibrational properties of single-walled carbon nanotubes. Nanotechnology, 9: 184-191, 1998.
[11] S. H. Tolbert and A. P. Alivisatos. The wurtzite to rock salt structural transformation in CdSe nanocrystals under high pressure. J. Chem. Phys. , 102: 4642-4656, 1995.
[12] C. -C. Chen, A. B. Herhold, C. S. Johnson, and A. P. Alivisatos. Size Dependence of Structural Metastability in Semiconductor Nanocrystals. Science, 276: 398-401, 1997.
[13] K. Jacobs, D. Zaziski, E. C. Scher, A. B. Herhold, and A. P. Alivisatos. Activation Volumes for Solid-Solid Transformations in Nanocrystals. Science, 293: 1803-1806, 2001.
[14] K. Jacobs, J. Wickham, and A. P. Alivisatos. Threshold Size for Ambient Metastability of Rocksalt CdSe Nanocrystals. J. Phys. Chem. B, 106: 3759-3762, 2002.
[15] D. Zaziski, S. Prilliman, E. C. Scher, M. Casula, J. Wickham, S. M. Clark, and A. P. Alivisatos. Critical Size for Fracture during Solid-Solid Phase Transformations. Nano Lett. , 4: 943-946, 2004.
[1] M. P. Allen and D. J. Tildesley. Computer Simulation of Liquids. Oxford University Press, 1987.
[2] K. Binder, J. Horbach, W. Kob, W. Paul, and F. Varnik. Molecular dynamics simulations. Journal of Physics: Condensed Matter, 16: S429-S453, 2004.
[3] F. Ercolessi. A Molecular Dynamics Primer. Spring College in Computational Physics, 1997. Online tutorial, http://www.ud.infn.it/ercolessi/md/.
[4] D. FrenkeI and B. Stair. Understanding Molecular Simulation: From Algorithms to Applications. Academic Press, San Diego, USA, 1996.
[5] J. E. Lennard-Jones. Cohesion. Proceedings of the Physical Society, 43: 461-482, 1931.
[6] J. Tersoff. Modeling solid-state chemistry: Interatomic potentials for multicomponent systems. Physical Review B, 39: 5566-5568, 1989.
[7] D. W. Brenner. Empirical potential for hydrocarbons for use in simulating the chemical vapor deposition of diamond films. Physical Review B, 42: 9458-9471, 1990.
[8] D. W. Brenner, O. A. Shenderova, J. A. Harrison, S. J. Stuart, B. Ni, and S. B. Sinnott. A second-generation reactive empirical bond order (REBO) potential energy expression for hydrocarbons. Journal of Physics: Condensed Matter, 14: 783-802, 2002.
[9] N. A. Marks. Generalizing the environment-dependent interaction potential for carbon. Physical Review B, 63: 035401, 2000.
[10] D. G. Pettifor and I. I. Oleinik. Analytic bond-order potentials beyond Tersoff-Brenner. I. Theory. Physical Review B, 59: 8487-8499, 1999.
[11] I. I. Oleinik and D. G. Pettifor. Analytic bond-order potentials beyond Tersoff-Brenner. Ⅱ. Application to the hydrocarbons. Physical Review B, 59: 8500-8507, 1999.
[12] G. C. Abell. Empirical chemical pseudopotential theory of molecular and metallic bonding. Physical Review B, 31: 6184-6196, 1985.
[13] J. Tersoff. New empirical model for the structural properties of silicon. Physical Review Letters, 56: 632-635, 1986.
[14] J. Tersoff. New empirical approach for the structure and energy of covalent systems. Physical Review B, 37: 6991-7000, 1988.
[15] L. Verlet. Computer 'experiments' classical fluids. I. Thermodynamical properties of Lennard-Jonesmolecules. Phys. Rev. , 59: 98-103, 1967.
[16] R. W. Honeycutt. The potential calculation and some apptications. Methods in Computational Physics, 9: 136-211, 1970.
[17] W. C. Swope, H. C. Anderson, P. H. Berens, and K. R. Wilson. A computer simulation method for the calculation of equilibrium constants for the formation of physical clusters of molecules: applications to small water clusters. J. Chem. Phys. , 76: 637-649, 1982.
[18] D. Beeman. Some multistep methods for use in molecular dynamics calculations. J. Comput. Phys. , 20: 130-139, 1976.
[19] K. H. Hoffmann, and M. Schreiber. Computational Physics. Berlin Heidelberg: Springer-Verlag, 268-326, 1986.
[20] H. J. C. Berendsen, P. M. Postma, and W. F. V. Gunsteren. Molecular dynamics with coupling to an external bath. J. Chem. Phys., 81: 3684-3690, 1984.
[21] S. Nose. Constant Temperature Molecular Dynamics Methods. Progress of Theoretical Physics Supplement, 103: 1-46, 1991.
[22] S. Nose. A molecular dynamics method for simulations in the canonical ensemble. Molecular Physics, 52: 255-268, 1984.
[23] W. G. Hoover. Canonical dynamics: Equilibrium phase-space distributions. Physical Review A, 31: 1695-1697, 1985.
[24] M. Parrinello and A. Rahman. Polymorphic transitions in single crystals: A new molecular dynamics method. Journal of Applied Physics, 52: 7182-7190, 1981.
[25] D. Y. Sun and X. G. Gong. A new constant-pressure molecular dynamics method for finite systems. Journal of Physics: Condensed Matter, 14: L487-L493, 2002.
[1] J. P. Lu. Elastic Properties of Carbon Nanotubes and Nanoropes. Phys. Rev. Lett. , 79: 1297-1300, 1997.
[2] Daniel Sanchez-Portal, Emilio Artacho, and JoseM. Soler, Angel Rubio, and Pablo Ordejon. Ab initio structural, elastic, and vibrational properties of carbon nanotubes. Phys. Rev. B, 59: 12678-12688, 1999.
[3] Zhou Xin, Zhou Jianjun, and Ou-Yang Zhong-can. Strain energy and Young's modulus of single-wall carbon nanotubes calculated from electronic energy-band theory. Phys. Rev. B, 62: 13692-13696, 2000.
[4] Vikram Gadagkar, Prabal K. Maiti, Yves Lansac, A. Jagota, and A. K. Sood. Collapse of double-walled carbon nanotube bundles under hydrostatic pressure. Phys. Rev. B, 73: 085402(6), 2006.
[5] U. D. Venkateswaran, A. M. Rao, E. Richter, M. Menon, A. Rinzler, R. E. Smalley, and P. C. Eklund. Probing the single-wall carbon nanotube bundle: Raman scattering under high pressure. Phys. Rev. B, 59: 10928-10934, 1999.
[6] J. Tang, L. C. Qin. T. Sasaki, M. Yudasaka, A. Matsushita, and S. Iijima. Compressibility and Polygonization of Single-Walled Carbon Nanotubes under Hydrostatic Pressure. Phys. Rev. Lett. , 85: 1887-1889, 2000.
[7] S. P. Chan, W. L. Yim, X. G. Gong, and Z. F. Liu. Carbon nanotube bundles under high pressure: Transformation to Iow-symmetry structures. Phys. Rev. B, 68: 075404(7), 2003.
[8] J. A. Elliott, J. K. W. Sandler, A. H. Windle, R. J. Young, M. S. P. Shaffer. Collapse of Single-Wall Carbon Nanotubes is Diameter Dependent. Phys. Rev. Lett., 92: 095501-095504, 2004.
[9] D. Y. Sun, D. J. Shu, M. Ji, Feng Liu, M. Wang, and X. G. Gong. Pressure-induced hard-to-soft transition of a single carbon nanotube. Phys. Rev. B, 70: 165417(5), 2004.
[10] X. H. Zhang, D. Y. Sun, and X. G. Gong. Structure and phase transitions of single-wall carbon nanotube bundles under hydrostatic pressure. Phys. Rev. B, 70: 035422(5), 2004.
[11] Q. Zheng and Q. Jiang. Multiwalled Carbon Nanotubes as Gigahertz Oscillators. Phys. Rev. Lett. 88: 045503-045505, 2002.
[12] S. B. Legoas, V. R. Coluci, S. F. Brags, P. Z. Coura, S. O. Dantas, and D. S. Galvao. Molecular-Dynamics Simulations of Carbon Nanotubes as Gigahertz Oscillators. Phys. Rev. Lett. 90: 055504-055507, 2003.
[13] G. Chen, S. Bandow, E. R. Margine, C. Nisoli, A. N. Kolmogorov, Vincent H. Crespi, R. Gupta, G. U. Sumanasekera, S. Iijima, P. C. Eklund. Chemically Doped Double-Walled Carbon Nanotubes: Cylindrical Molecular Capacitors. Phys. Rev. Lett.90: 257403-257406, 2003.
[14] P. Puech, H. Hubel, D. J. Dunstan, R. R. Bacsa, C. Laurent, and W. S. Bacsa. DiscontinuousTangential Stress in DoubleWall Carbon Nanotubes. Phys. Rev. Lett, 93: 095506(4), 2004.
[15] J. Arvanitidis, D. Christofilos, K. Papagelis, K. S. Andrikopoulos, T. Takenobu, Y. Iwasa, H. Kataura, S. Ves, and G. A. Kourouklis. Pressure screening in the interior of primary shells in double-wall carbon nanotubes. Phys. Rev. B, 71: 125404(5), 2005.
[16] R. Pfeiffer, F. Simon, H. Kuzmany, and V. N. Popov. Fine structure of the radial breathing mode of double-wall carbon nanotubes. Phys. Rev. B, 72: 161404-161405, 2005.
[17] P. Puech, A. Bassil, J. Gonzalez, Ch. Power, E. Flahaut, S. Barrau, Ph. Demont, C. Lacabanne, E. Perez, and W. S. Bacsa. Similarities in the Raman RBM and D bands in double-wall carbon nanotubes. Phys. Rev. B, 72: 155436(6), 20O5.
[18] D. Y. Sun, and X. G. Gong. A new constant-pressure molecular dynamics method for finite systems. J. Phys.: Condens. Matter,14:L487-L493, 2002.
[19] W. G. Hoover. Canonical dynamics: Equilibrium phase-space distributions. Physical Review A, 31: 1695-1697, 1985.
[20] S. Nose. A molecular dynamics method for simulations in the canonical ensemble. Molecular Physics, 52:255-268, 1984.
[21] J. Tersoff. Empirical Interatomic Potential for Carbon, with Applications to Amorphous Carbon. Phys. Rev. Lett, 61: 2879-2882, 1988.
[22] D. W. Brenner. Empirical potential for hydrocarbons for use in simulating the chemical vapor deposition of diamond films. Physical Review B, 42: 9458-9471, 1990.
[23] D. H. Robertson, D. W. Brenner, and J. W. Mintmire. Energetics of nanoscale graphitic tubules. Phys. Rev. B, 45: 12592-12595, 1992.
[24] M. B. Nardelli, B. I. Yakobson, and J. Bernholc. Brittle and Ductile Behavior in Carbon Nanotubes. Phys. Rev. Lett., 81: 4656-4659, 1998.
[25] Y. Xia, Y. Ma, Y. Xing, Y. Mu, C. Tan, and L. Mei. Growth and defect formation of single-wall carbon nanotubes. Phys. Rev. B, 61: 11088-11092, 2000.
[26] A. N. Kolmogorov and V. H. Crespi. Smoothest Bearings: Interlayer Sliding in Multiwalled Carbon Nanotubes. Phys. Rev. Lett., 85: 4727-4730, 2000.
[27] Y. Ma, Y. Xia, M. Zhao, R. Wang, and L. Mei. Effective hydrogen storage in single-wall carbon nanotubes. Phys. Rev. B, 63: 115422(6), 2001.
[28] L. Henrard, E. Hernandez, P. Bernier, and A. Rubio. van der Waals interaction in nanotube bundles: Consequences on vibrational modes. Phys. Rev. B, 60: R8521-R8524, 1999.
[29] A. N. Kolmogorov and V. H. Crespi. Smoothest Bearings: Interlayer Sliding in Multiwalled Carbon Nanotubes. Phys. Rev. Lett., 85: 4727-4730, 2000.
[30] Wanlin Guo, Yufeng Guo, Huajian Gao, Quanshui Zheng, and Wenyu Zhong. Energy Dissipation in Gigahertz Oscillators from Multiwalled Carbon Nanotubes. Phys. Rev. Lett., 91: 125501-125504, 2003.
[31] Lei Liu, C. S. Jayanthi, and Shi-Yu Wu. Linking vibrational dynamics to characteristics of Iocal electronic structure: Local analysis of dynamics of the relaxed Si_(87) cluster. Phys. Rev. B, 68: 012303-012307, 2003.
[32] R. Saito, G. Dresselha, us, and M. S. Dresselhaus, Physical Properties of Carbon Nanotubes (Imperial College, 2003), p. 200.
[1] Dresselhaus MS, Williams KA, Eklund PC. Hydrogen adsorption in carbon materials. MRS Bull; 24: 45-50, 1999.
[2] Dillon AC, Heben MJ. Hydrogen storage using carbon adsorbents: past, present and future. Appl Phys A, Mater Sci Process, 72: 133-42, 2001.
[3] Dillon AC, Jones KM, Bekkedahl TA, Kiang CH, Bethune DS, Heben MJ, Nature (London) 386: 377-379, 1997.
[4] Chen P, ChenWu X, Lin J, Tan KL. High H_2 uptake by alkali-doped carbon nanotubes under ambient pressure and moderate temperatures. Science; 285: 91-3, 1999.
[5] Liu C, Fan YY, Liu M, Cong HT, Cheng HM, Dresselhaus MS. Hydrogen storage in singlewalled carbon nanotubes at room temperature. Science, 286: 1127-9, 1999.
[6] Simonyan V V, Uiep P, and Johuaon J K. J. Chem. Phys, 111 (21): 9778-978, 1999.
[7] Q. Y. Wang, and J. K. Johnson. J. Chem. Phys, 110(1): 577-586, 1999.
[8] Vidali G, Ihm G, Kim HY, Cole MW. Potentials of physical adsorption. Surf Sci Rep. 12: 133-81, 1991.
[9] Mattera L, Rosatelli F, Salvo C, Tommasini F, Valbusa U, Vidali G. Selective adsorption of 1h2 and 2h2 on the (0001) graphite surface. Surf Sci 93: 515-25, 1980.
[10] Silvera Isaac F. The solid molecular hydrogens in the condensed phase: fundamentals and static properties. Rev Mod Phys, 52: 393-452, 1980.
[11] Mao HK, Hemley Russell J. Ultrahigh-pressure transitions in solid hydrogen. Rev Mod Phys, 66: 671-92, 1994.
[12] Mao WL, Mao HK. Hydrogen storage in molecular compounds. Proc Nat Acad Sci USA 101:708-10, 2004.
[13] Monthioux M. Filling singlewall carbon nanotubes. Carbon, 40: 1809-23, 2002.
[14] Sloan Jeremy, Kirkland Angus I, Hutchison John L, Green Malcolm H. Structural characterization of atomically regulated nanocrystals formed within singlewalled carbon nanotubes using electron microsocopy. Acc Chem Res, 35: 1054-62, 2002.
[15] L. Sun, F. Banhart, A. V. Krasheninnikov, J. A. Rodriguez Manzo, M. Terrones, and P. M. Ajayan. Carbon Nanotubes as High Pressure Cylinders and Nanoextruders. Science,312: 1199-1202, 2006.
[16] Ponder JW, Richards FM. An efficient Newton-like method for molecular mechanics energy minimization of large molecules. J Comput Chem, 8: 1016-24, 1987.
[17] Allinger NL, Yuh YH, Lii JH. Molecular mechanics. The mm3 force field for hydrocarbons. J Am Chem Soc, 111: 8551-66, 1989.
[18] Allinger Norman L, Durkin Kathleen A. Van der Waals effects between hydrogen and first row atoms in molecular mechanics (mm3/ mm4). J Comput Chem, 21: 1229-42, 2000.
[19] Kelly E, Seth M, Ziegler T. Calculation of free energy profiles for elementary bimolecular reactions by a initio molecular dynamics: sampling methods and thermostat considerations. J Phys Chem A, 108 :2167-80,2004.
[20] Mills RL, Liebenberg DH, Bronson JC, Schmidt LC. Equation of state of fluid nh2 from pvt and sound velocity measurements to 20 kbar. J Chem Phys, 66: 3076-84, 1977.
[21] Liebenberg DH, Mills RL, Bronson JC. High-pressure apparatus for simultaneous adiabatic and isothermal compressibility measurements data on argon to 13 kbar. J Appl Phys, 45: 741-7, 1974.
[22] Chan SP, Yim WL, Gong XG, Liu ZF. Carbon nanotube bundles under high pressure: transformation to low symmetry structures. Phys Rev B, 68: 075404, 2003.
[23] Sun DY, Shu DJ, Ji M, Liu F, Wang M, Gong XG. Pressure induced hard soft transition of a single carbon nanotube. Phys Rev B, 70: 165417, 2004.
[1] Y. N. Xu and W. Y. Ching. Electronic, optical, and structural properties of some wurtzite crystals. Phys. Rev. B, 48: 4335-4351, 1993.
[2] J. K. Burdett and T. J. McLarnan. A study of the arsenic, black phosphorus, and other structures derived from rock salt by bond-breaking processes. Ⅰ. Structural enumeration. J. Chem. Phys., 75: 5764-5773, 1981.
[3] F. Shimojo, S. Kodiyalam, I. Ebbsjo, R. K. Kalia, A. Nakano, and P. Vashishta. Atomistic mechanisms for wurtzite-to-rocksalt structural transformation in cadmium selenide under pressure. Phys. Rev. B, 70: 184111(6), 2004.
[4] J. R. Chelikowsky and J. K. Burdett. Ionicity and the Structural Stability of Solids. Phys. Rev. Lett., 56: 961-964, 1986.
[5] N. E. Christensen, S. Satpathy, and Z. Pawlowska. Bonding and ionicity in semiconductors. Phys. Rev. B, 36: 1032-1050, 1987.
[6] P. Perlin, C. Jauberthie-Carillon, J. P. Itie, A. S. Miguel, I. Grzegory, and A. Polian. Raman scattering and x-ray-absorption spectroscopy in gallium nitride under high pressure. Phys. Rev. B, 45: 83-89, 1992.
[7] H. Xia, Q. Xia, and A. L. Ruoff. High-pressure structure of gallium nitride: Wurtzite-to-rocksalt phase transition. Phys. Rev. B, 47: 12925-12928, 1993.
[8] M. Yoshida, A. Onodera, M. Ueno, K. Takemura, and O. Shimomura. Pressure-induced phase transition in SiC. Phys. Rev. B, 48: 10587-10590, 1993.
[9] T. Sekine and T. Kobayashi, ibid. 55, 8034 (1997).
[10] A. N. Mariano and E. P. Warekois. High Pressure Phases of Some Compounds of Groups Ⅱ-Ⅵ. Science, 142: 672-675, 1963.
[11] J. N. Wickham, A. B. Herhold, and A. P. Alivisatos. Shape Change as an Indicator of Mechanism in the High-Pressure Structural Transformations of CdSe Nanocrystals. Phys. Rev. Lett., 84: 923-926, 2000.
[12] M. D. Knudson, Y. M. Gupta, and A. B. Kunz. Transformation mechanism for the pressure-induced phase transition in shocked CdS. Phys. Rev. B 59: 11704-11715, 1999.
[13] S. Kodiyalam, R. K. Kalia, A. Nakano, and P. Vashishta. Multiple Grains in Nanocrystals: Effect of Initial Shape and Size on Transformed Structures Under Pressure. Phys. Rev. Lett., 93: 203401-203404, 2004.
[14] B. J. Morgan, and P. A. Madden. Pressure-Driven Sphalerite to Rock Salt Transition in Ionic Nanocrystals: A Simulation Study. Nano Lett., 4: 1581-1585, 2004.
[15] D. Zahn, Y. Grin, and S. Leoni. Mechanism of the pressure-induced wurtzite to rocksalt transition of CdSe. Phys. Rev. B, 72: 064110(7), 2005.
[16] S. Limpijumnong and W. R. L. Lambrecht. Homogeneous Strain Deformation Path for the Wurtzite to Rocksalt High-Pressure Phase Transition in GaN. Phys. Rev. Lett., 86: 91-94, 2001.
[17] N. J. Lee, R. K. Kalia, A. Nakano, and P. Vashishta. Pressure-induced struc-tural transformations in cadmium selenide nanorods. Appl. Phys. Lett., 89: 093101-093103, 2006.
[18] S. Limpijumnong and S. Jungthawan. First-principles study of the wurtzite-to-rocksalt homogeneous transformation in ZnO: A case of a low-transformation barrier. Phys. Rev. B, 70: 054104-054107, 2004.
[19] M. S. Miao and Walter R. L. Lambrecht. Unified path for high-pressure transitions of SiC polytypes to the rocksalt structure. Phys. Rev. B, 68: 092103-092106, 2003.
[20] C. Molteni, R. Martonak, M. Parrinello. First principles molecular dynamics simulations of pressure-induced structural transformations in silicon clusters. J. Chem. Phys., 114: 5358-5365, 2001.
[21] M. Ueno, M. Yoshida, A. Onodera, O. Shimomura, and K. Takemura. Stability of the wurtzite-type structure under high pressure: CaN and InN. Phys. Rev. B, 49: 14-21, 1994.
[22] M. Ueno, A. Onodera, O. Shimomura, and K. Takemura. X-ray observation of the structural phase transition of aluminum nitride under high pressure. Phys. Rev. B, 45: 10123-10126, 1992.
[23] P. Perlin, C. Jauberthie-Carillon, J. P. Itie, A. San Miguel, I. Grzegory, and A. Polian. High pressure phase transition in gallium nitride. High Press. Res., 71: 96-98, 1991.
[24] P. Perlin, I. Gorczyca, S. Porowski, T. Suski, N. E. Christensen, and A. Polian. Ⅲ-Ⅴ Semiconducting Nitrides: Physical Properties under Pressure. Jpn. J. Appl. Phys., Suppl., 32: 334-339, 1993.
[25] S. Uehara, T. Masamoto, A. Onodera, M. Ueno, O. Shimomura, and K. Takemura. Equation of state of the rocksalt phase of Ⅲ-Ⅴ nitrides to 72 GPa or higher. J. Phys. Chem. Solids, 58: 2093-2099, 1997.
[26] N. E. Christensen and I. Gorezyca. Optical and structural properties of Ⅲ-Ⅴ nitrides under pressure. Phys. Rev. B, 50: 4397-4415, 1994.
[27] A. Munoz and K. Kunc. High-pressure phase of gallium nitride. Phys. Rev. B, 44: 10372-10373, 1991.
[28] B. B. Karki and R. M. Wentzcovitch. Vibrational and quasiharmonic thermal properties of CaO under pressure. Phys. Rev. B, 68: 224304(6), 2003.
[29] H. Zhang, B. Gilbert, F. Huang, and J. F. Banfield. Water-driven structure transformation in nanoparticles at room temperature. Nature,(London)424: 1025-1029, 2003.
[30] S. Vemparala, R. K. Kalia, A. Nakano, and P. Vashishta. Electric field induced switching of poly(ethylene glycol) terminated self-assembled monolayers: A parallel molecular dynamics simulation. J. Chem. Phys., 121: 5427-5433, 2004.
[31] S. H. Tolbert and A. P. Alivisatos. The wurtzite to rock salt structural transformation in CdSe nanocrystals under high pressure. J. Chem. Phys., 102: 4642-4656, 1995.
[32] C.-C. Chen, A. B. Herhold, C. S. Johnson, and A. P. Alivisatos. Size Dependence of Structural Metastability in Semiconductor Nanocrystals. Science, 276: 398-401, 1997.
[33] K. Jacobs, D. Zaziski, E. C. Scher, A. B. Herhold, and A. P. Alivisatos. Activation Volumes for Solid-Solid Transformations in Nanocrystals. Science, 293: 1803-1806, 2001.
[34] K. Jacobs, J. Wickham, and A. P. Alivisatos. Threshold Size for Ambient Metastability of Rocksalt CdSe Nanocrystals. J. Phys. Chem. B, 106: 3759-3762, 2002.
[35] D. Zaziski, S. Prilliman, E. C. Scher, M. Casula, J. Wickham, S. M. Clark, and A. P. Alivisatos. Critical Size for Fracture during Solid-Solid Phase Transformations. Nano Lett., 4: 943-946, 2004.
[36] Michael Grunwald, Eran Rabani, and and Christoph Dellago. Mechanisms of the Wurtzite to Rocksalt Transformation in CdSe Nanocrystals. Phys. Rev. Lett., 96: 255701-255704, 2006.
[37] S. M. Sharma and Y. M. Gupta. Wurtzite-to-rocksalt structural transfor-mation in cadmium sulphide shocked along the a axis. Phys. Rev. B, 58: 5964-5971, 1998.
[38] S. Limpijumnong and W. R. L. Lambrecht. Theoretical study of the relative stability of wurtzite and rocksalt phases in MgO and GaN. Phys. Rev. B, 63: 104103(11), 2001.
[39] H. Sowa, Acta Crystallogr., Sect. A: Found. Crystallogr. On the transition from the wurtzite to the NaCl type. 57: 176-182, 2001.
[40] M. Wilson and P. A. Madden. Transformations between tetrahedrally and octahedrally coordinated crystals: the wurtzite to rocksalt and blende to rocksalt mechanisms. J. Phys.: Condens. Matter, 14: 4629-4643, 2002.
[41] C. B. Barber, D. P. Dobkin, and H. Huhdanpaa, ACM Trans. Math. Softw. 22, 469 (1996).
[42] E. Rabani. An interatomic pair potential for cadmium selenide. J. Chem. Phys., 116: 258-262, 2002.
[43] E. Rabani. Structure and electrostatic properties of passivated CdSe nanocrystals. J. Chem. Phys. 115: 1493-1497, 2001.
[44] S. Kodiyalam, R. K. Kalia H. Kikuchi, A. Nakano, F. Shimojo, and P. Vashishta. Grain Boundaries in Gallium Arsenide Nanocrystals Under Pressure: A Parallel Molecular-Dynamics Study. Phys. Rev. Lett., 86: 55-58, 2001.
[45] A. J. Kulkarni, M. Zhou, K. Sarasamak, and S. Limpijumnong. Novel Phase Transformation in ZnO Nanowires under Tensile Loading. Phys. Rev. Lett., 97: 105502-105505, 2006.
[2] S. Iijima. Helical microtubules of graphitic carbon. Nature, 354: 56-58, 1991.
[3] T. W. Ebbesen, and P. M. Ajayan. Large-scale synthesis of carbon nanotubes. Nature, 358: 6383-6385, 1992.
[4] S. Iijima and T. Ichihashi. Single-shell carbon nanotubes of 1-nm diameter. Nature, 363: 603-605, 1993.
[5] D. S. Bethune, C. H. Klang, M. S. de Vries, G. Gorman, R. Savoy, J. Vazquez, and R. Beyers. Cobalt-catalysed growth of carbon nanotubes with singleatomic- layer walls. Nature, 363: 605-607, 1993.
[6] A. Thess, et al., Crystalline Ropes of Metallic Carbon Nanotubes. Science, 273: 483-487, 1996.
[7] C. Liu, Y. Y. Fan, M. Liu, H. T. Cong, H. M. Cheng, and M. S. Dresselhaus. Hydrogen Storage in Single-Walled Carbon Nanotubes at Room Temperature. Science, 286: 1127-1129, 1999.
[8] C. Liu, H. T. Cong, F. Li, P. H. Tan, H. M. Cheng, K. Lug and B. L. Zhou. Semi-continuous synthesis of single-walled carbon nanotubes by a hydrogen arc discharge method. Carbon, 37: 1865-1868, 1999.
[9] J. Tersoff, and R. S. Ruoff. Structural Properties of a Carbon-Nanotube Crystal. Phys. Rev. Lett. , 73: 676-679, 1994.
[10] Gao Gh, Cagin T, and Goddard WA. Energetics, structure, mechanical and vibrational properties of single-walled carbon nanotubes. Nanotechnology, 9: 184-191, 1998.
[11] S. H. Tolbert and A. P. Alivisatos. The wurtzite to rock salt structural transformation in CdSe nanocrystals under high pressure. J. Chem. Phys. , 102: 4642-4656, 1995.
[12] C. -C. Chen, A. B. Herhold, C. S. Johnson, and A. P. Alivisatos. Size Dependence of Structural Metastability in Semiconductor Nanocrystals. Science, 276: 398-401, 1997.
[13] K. Jacobs, D. Zaziski, E. C. Scher, A. B. Herhold, and A. P. Alivisatos. Activation Volumes for Solid-Solid Transformations in Nanocrystals. Science, 293: 1803-1806, 2001.
[14] K. Jacobs, J. Wickham, and A. P. Alivisatos. Threshold Size for Ambient Metastability of Rocksalt CdSe Nanocrystals. J. Phys. Chem. B, 106: 3759-3762, 2002.
[15] D. Zaziski, S. Prilliman, E. C. Scher, M. Casula, J. Wickham, S. M. Clark, and A. P. Alivisatos. Critical Size for Fracture during Solid-Solid Phase Transformations. Nano Lett. , 4: 943-946, 2004.
[1] M. P. Allen and D. J. Tildesley. Computer Simulation of Liquids. Oxford University Press, 1987.
[2] K. Binder, J. Horbach, W. Kob, W. Paul, and F. Varnik. Molecular dynamics simulations. Journal of Physics: Condensed Matter, 16: S429-S453, 2004.
[3] F. Ercolessi. A Molecular Dynamics Primer. Spring College in Computational Physics, 1997. Online tutorial, http://www.ud.infn.it/ercolessi/md/.
[4] D. FrenkeI and B. Stair. Understanding Molecular Simulation: From Algorithms to Applications. Academic Press, San Diego, USA, 1996.
[5] J. E. Lennard-Jones. Cohesion. Proceedings of the Physical Society, 43: 461-482, 1931.
[6] J. Tersoff. Modeling solid-state chemistry: Interatomic potentials for multicomponent systems. Physical Review B, 39: 5566-5568, 1989.
[7] D. W. Brenner. Empirical potential for hydrocarbons for use in simulating the chemical vapor deposition of diamond films. Physical Review B, 42: 9458-9471, 1990.
[8] D. W. Brenner, O. A. Shenderova, J. A. Harrison, S. J. Stuart, B. Ni, and S. B. Sinnott. A second-generation reactive empirical bond order (REBO) potential energy expression for hydrocarbons. Journal of Physics: Condensed Matter, 14: 783-802, 2002.
[9] N. A. Marks. Generalizing the environment-dependent interaction potential for carbon. Physical Review B, 63: 035401, 2000.
[10] D. G. Pettifor and I. I. Oleinik. Analytic bond-order potentials beyond Tersoff-Brenner. I. Theory. Physical Review B, 59: 8487-8499, 1999.
[11] I. I. Oleinik and D. G. Pettifor. Analytic bond-order potentials beyond Tersoff-Brenner. Ⅱ. Application to the hydrocarbons. Physical Review B, 59: 8500-8507, 1999.
[12] G. C. Abell. Empirical chemical pseudopotential theory of molecular and metallic bonding. Physical Review B, 31: 6184-6196, 1985.
[13] J. Tersoff. New empirical model for the structural properties of silicon. Physical Review Letters, 56: 632-635, 1986.
[14] J. Tersoff. New empirical approach for the structure and energy of covalent systems. Physical Review B, 37: 6991-7000, 1988.
[15] L. Verlet. Computer 'experiments' classical fluids. I. Thermodynamical properties of Lennard-Jonesmolecules. Phys. Rev. , 59: 98-103, 1967.
[16] R. W. Honeycutt. The potential calculation and some apptications. Methods in Computational Physics, 9: 136-211, 1970.
[17] W. C. Swope, H. C. Anderson, P. H. Berens, and K. R. Wilson. A computer simulation method for the calculation of equilibrium constants for the formation of physical clusters of molecules: applications to small water clusters. J. Chem. Phys. , 76: 637-649, 1982.
[18] D. Beeman. Some multistep methods for use in molecular dynamics calculations. J. Comput. Phys. , 20: 130-139, 1976.
[19] K. H. Hoffmann, and M. Schreiber. Computational Physics. Berlin Heidelberg: Springer-Verlag, 268-326, 1986.
[20] H. J. C. Berendsen, P. M. Postma, and W. F. V. Gunsteren. Molecular dynamics with coupling to an external bath. J. Chem. Phys., 81: 3684-3690, 1984.
[21] S. Nose. Constant Temperature Molecular Dynamics Methods. Progress of Theoretical Physics Supplement, 103: 1-46, 1991.
[22] S. Nose. A molecular dynamics method for simulations in the canonical ensemble. Molecular Physics, 52: 255-268, 1984.
[23] W. G. Hoover. Canonical dynamics: Equilibrium phase-space distributions. Physical Review A, 31: 1695-1697, 1985.
[24] M. Parrinello and A. Rahman. Polymorphic transitions in single crystals: A new molecular dynamics method. Journal of Applied Physics, 52: 7182-7190, 1981.
[25] D. Y. Sun and X. G. Gong. A new constant-pressure molecular dynamics method for finite systems. Journal of Physics: Condensed Matter, 14: L487-L493, 2002.
[1] J. P. Lu. Elastic Properties of Carbon Nanotubes and Nanoropes. Phys. Rev. Lett. , 79: 1297-1300, 1997.
[2] Daniel Sanchez-Portal, Emilio Artacho, and JoseM. Soler, Angel Rubio, and Pablo Ordejon. Ab initio structural, elastic, and vibrational properties of carbon nanotubes. Phys. Rev. B, 59: 12678-12688, 1999.
[3] Zhou Xin, Zhou Jianjun, and Ou-Yang Zhong-can. Strain energy and Young's modulus of single-wall carbon nanotubes calculated from electronic energy-band theory. Phys. Rev. B, 62: 13692-13696, 2000.
[4] Vikram Gadagkar, Prabal K. Maiti, Yves Lansac, A. Jagota, and A. K. Sood. Collapse of double-walled carbon nanotube bundles under hydrostatic pressure. Phys. Rev. B, 73: 085402(6), 2006.
[5] U. D. Venkateswaran, A. M. Rao, E. Richter, M. Menon, A. Rinzler, R. E. Smalley, and P. C. Eklund. Probing the single-wall carbon nanotube bundle: Raman scattering under high pressure. Phys. Rev. B, 59: 10928-10934, 1999.
[6] J. Tang, L. C. Qin. T. Sasaki, M. Yudasaka, A. Matsushita, and S. Iijima. Compressibility and Polygonization of Single-Walled Carbon Nanotubes under Hydrostatic Pressure. Phys. Rev. Lett. , 85: 1887-1889, 2000.
[7] S. P. Chan, W. L. Yim, X. G. Gong, and Z. F. Liu. Carbon nanotube bundles under high pressure: Transformation to Iow-symmetry structures. Phys. Rev. B, 68: 075404(7), 2003.
[8] J. A. Elliott, J. K. W. Sandler, A. H. Windle, R. J. Young, M. S. P. Shaffer. Collapse of Single-Wall Carbon Nanotubes is Diameter Dependent. Phys. Rev. Lett., 92: 095501-095504, 2004.
[9] D. Y. Sun, D. J. Shu, M. Ji, Feng Liu, M. Wang, and X. G. Gong. Pressure-induced hard-to-soft transition of a single carbon nanotube. Phys. Rev. B, 70: 165417(5), 2004.
[10] X. H. Zhang, D. Y. Sun, and X. G. Gong. Structure and phase transitions of single-wall carbon nanotube bundles under hydrostatic pressure. Phys. Rev. B, 70: 035422(5), 2004.
[11] Q. Zheng and Q. Jiang. Multiwalled Carbon Nanotubes as Gigahertz Oscillators. Phys. Rev. Lett. 88: 045503-045505, 2002.
[12] S. B. Legoas, V. R. Coluci, S. F. Brags, P. Z. Coura, S. O. Dantas, and D. S. Galvao. Molecular-Dynamics Simulations of Carbon Nanotubes as Gigahertz Oscillators. Phys. Rev. Lett. 90: 055504-055507, 2003.
[13] G. Chen, S. Bandow, E. R. Margine, C. Nisoli, A. N. Kolmogorov, Vincent H. Crespi, R. Gupta, G. U. Sumanasekera, S. Iijima, P. C. Eklund. Chemically Doped Double-Walled Carbon Nanotubes: Cylindrical Molecular Capacitors. Phys. Rev. Lett.90: 257403-257406, 2003.
[14] P. Puech, H. Hubel, D. J. Dunstan, R. R. Bacsa, C. Laurent, and W. S. Bacsa. DiscontinuousTangential Stress in DoubleWall Carbon Nanotubes. Phys. Rev. Lett, 93: 095506(4), 2004.
[15] J. Arvanitidis, D. Christofilos, K. Papagelis, K. S. Andrikopoulos, T. Takenobu, Y. Iwasa, H. Kataura, S. Ves, and G. A. Kourouklis. Pressure screening in the interior of primary shells in double-wall carbon nanotubes. Phys. Rev. B, 71: 125404(5), 2005.
[16] R. Pfeiffer, F. Simon, H. Kuzmany, and V. N. Popov. Fine structure of the radial breathing mode of double-wall carbon nanotubes. Phys. Rev. B, 72: 161404-161405, 2005.
[17] P. Puech, A. Bassil, J. Gonzalez, Ch. Power, E. Flahaut, S. Barrau, Ph. Demont, C. Lacabanne, E. Perez, and W. S. Bacsa. Similarities in the Raman RBM and D bands in double-wall carbon nanotubes. Phys. Rev. B, 72: 155436(6), 20O5.
[18] D. Y. Sun, and X. G. Gong. A new constant-pressure molecular dynamics method for finite systems. J. Phys.: Condens. Matter,14:L487-L493, 2002.
[19] W. G. Hoover. Canonical dynamics: Equilibrium phase-space distributions. Physical Review A, 31: 1695-1697, 1985.
[20] S. Nose. A molecular dynamics method for simulations in the canonical ensemble. Molecular Physics, 52:255-268, 1984.
[21] J. Tersoff. Empirical Interatomic Potential for Carbon, with Applications to Amorphous Carbon. Phys. Rev. Lett, 61: 2879-2882, 1988.
[22] D. W. Brenner. Empirical potential for hydrocarbons for use in simulating the chemical vapor deposition of diamond films. Physical Review B, 42: 9458-9471, 1990.
[23] D. H. Robertson, D. W. Brenner, and J. W. Mintmire. Energetics of nanoscale graphitic tubules. Phys. Rev. B, 45: 12592-12595, 1992.
[24] M. B. Nardelli, B. I. Yakobson, and J. Bernholc. Brittle and Ductile Behavior in Carbon Nanotubes. Phys. Rev. Lett., 81: 4656-4659, 1998.
[25] Y. Xia, Y. Ma, Y. Xing, Y. Mu, C. Tan, and L. Mei. Growth and defect formation of single-wall carbon nanotubes. Phys. Rev. B, 61: 11088-11092, 2000.
[26] A. N. Kolmogorov and V. H. Crespi. Smoothest Bearings: Interlayer Sliding in Multiwalled Carbon Nanotubes. Phys. Rev. Lett., 85: 4727-4730, 2000.
[27] Y. Ma, Y. Xia, M. Zhao, R. Wang, and L. Mei. Effective hydrogen storage in single-wall carbon nanotubes. Phys. Rev. B, 63: 115422(6), 2001.
[28] L. Henrard, E. Hernandez, P. Bernier, and A. Rubio. van der Waals interaction in nanotube bundles: Consequences on vibrational modes. Phys. Rev. B, 60: R8521-R8524, 1999.
[29] A. N. Kolmogorov and V. H. Crespi. Smoothest Bearings: Interlayer Sliding in Multiwalled Carbon Nanotubes. Phys. Rev. Lett., 85: 4727-4730, 2000.
[30] Wanlin Guo, Yufeng Guo, Huajian Gao, Quanshui Zheng, and Wenyu Zhong. Energy Dissipation in Gigahertz Oscillators from Multiwalled Carbon Nanotubes. Phys. Rev. Lett., 91: 125501-125504, 2003.
[31] Lei Liu, C. S. Jayanthi, and Shi-Yu Wu. Linking vibrational dynamics to characteristics of Iocal electronic structure: Local analysis of dynamics of the relaxed Si_(87) cluster. Phys. Rev. B, 68: 012303-012307, 2003.
[32] R. Saito, G. Dresselha, us, and M. S. Dresselhaus, Physical Properties of Carbon Nanotubes (Imperial College, 2003), p. 200.
[1] Dresselhaus MS, Williams KA, Eklund PC. Hydrogen adsorption in carbon materials. MRS Bull; 24: 45-50, 1999.
[2] Dillon AC, Heben MJ. Hydrogen storage using carbon adsorbents: past, present and future. Appl Phys A, Mater Sci Process, 72: 133-42, 2001.
[3] Dillon AC, Jones KM, Bekkedahl TA, Kiang CH, Bethune DS, Heben MJ, Nature (London) 386: 377-379, 1997.
[4] Chen P, ChenWu X, Lin J, Tan KL. High H_2 uptake by alkali-doped carbon nanotubes under ambient pressure and moderate temperatures. Science; 285: 91-3, 1999.
[5] Liu C, Fan YY, Liu M, Cong HT, Cheng HM, Dresselhaus MS. Hydrogen storage in singlewalled carbon nanotubes at room temperature. Science, 286: 1127-9, 1999.
[6] Simonyan V V, Uiep P, and Johuaon J K. J. Chem. Phys, 111 (21): 9778-978, 1999.
[7] Q. Y. Wang, and J. K. Johnson. J. Chem. Phys, 110(1): 577-586, 1999.
[8] Vidali G, Ihm G, Kim HY, Cole MW. Potentials of physical adsorption. Surf Sci Rep. 12: 133-81, 1991.
[9] Mattera L, Rosatelli F, Salvo C, Tommasini F, Valbusa U, Vidali G. Selective adsorption of 1h2 and 2h2 on the (0001) graphite surface. Surf Sci 93: 515-25, 1980.
[10] Silvera Isaac F. The solid molecular hydrogens in the condensed phase: fundamentals and static properties. Rev Mod Phys, 52: 393-452, 1980.
[11] Mao HK, Hemley Russell J. Ultrahigh-pressure transitions in solid hydrogen. Rev Mod Phys, 66: 671-92, 1994.
[12] Mao WL, Mao HK. Hydrogen storage in molecular compounds. Proc Nat Acad Sci USA 101:708-10, 2004.
[13] Monthioux M. Filling singlewall carbon nanotubes. Carbon, 40: 1809-23, 2002.
[14] Sloan Jeremy, Kirkland Angus I, Hutchison John L, Green Malcolm H. Structural characterization of atomically regulated nanocrystals formed within singlewalled carbon nanotubes using electron microsocopy. Acc Chem Res, 35: 1054-62, 2002.
[15] L. Sun, F. Banhart, A. V. Krasheninnikov, J. A. Rodriguez Manzo, M. Terrones, and P. M. Ajayan. Carbon Nanotubes as High Pressure Cylinders and Nanoextruders. Science,312: 1199-1202, 2006.
[16] Ponder JW, Richards FM. An efficient Newton-like method for molecular mechanics energy minimization of large molecules. J Comput Chem, 8: 1016-24, 1987.
[17] Allinger NL, Yuh YH, Lii JH. Molecular mechanics. The mm3 force field for hydrocarbons. J Am Chem Soc, 111: 8551-66, 1989.
[18] Allinger Norman L, Durkin Kathleen A. Van der Waals effects between hydrogen and first row atoms in molecular mechanics (mm3/ mm4). J Comput Chem, 21: 1229-42, 2000.
[19] Kelly E, Seth M, Ziegler T. Calculation of free energy profiles for elementary bimolecular reactions by a initio molecular dynamics: sampling methods and thermostat considerations. J Phys Chem A, 108 :2167-80,2004.
[20] Mills RL, Liebenberg DH, Bronson JC, Schmidt LC. Equation of state of fluid nh2 from pvt and sound velocity measurements to 20 kbar. J Chem Phys, 66: 3076-84, 1977.
[21] Liebenberg DH, Mills RL, Bronson JC. High-pressure apparatus for simultaneous adiabatic and isothermal compressibility measurements data on argon to 13 kbar. J Appl Phys, 45: 741-7, 1974.
[22] Chan SP, Yim WL, Gong XG, Liu ZF. Carbon nanotube bundles under high pressure: transformation to low symmetry structures. Phys Rev B, 68: 075404, 2003.
[23] Sun DY, Shu DJ, Ji M, Liu F, Wang M, Gong XG. Pressure induced hard soft transition of a single carbon nanotube. Phys Rev B, 70: 165417, 2004.
[1] Y. N. Xu and W. Y. Ching. Electronic, optical, and structural properties of some wurtzite crystals. Phys. Rev. B, 48: 4335-4351, 1993.
[2] J. K. Burdett and T. J. McLarnan. A study of the arsenic, black phosphorus, and other structures derived from rock salt by bond-breaking processes. Ⅰ. Structural enumeration. J. Chem. Phys., 75: 5764-5773, 1981.
[3] F. Shimojo, S. Kodiyalam, I. Ebbsjo, R. K. Kalia, A. Nakano, and P. Vashishta. Atomistic mechanisms for wurtzite-to-rocksalt structural transformation in cadmium selenide under pressure. Phys. Rev. B, 70: 184111(6), 2004.
[4] J. R. Chelikowsky and J. K. Burdett. Ionicity and the Structural Stability of Solids. Phys. Rev. Lett., 56: 961-964, 1986.
[5] N. E. Christensen, S. Satpathy, and Z. Pawlowska. Bonding and ionicity in semiconductors. Phys. Rev. B, 36: 1032-1050, 1987.
[6] P. Perlin, C. Jauberthie-Carillon, J. P. Itie, A. S. Miguel, I. Grzegory, and A. Polian. Raman scattering and x-ray-absorption spectroscopy in gallium nitride under high pressure. Phys. Rev. B, 45: 83-89, 1992.
[7] H. Xia, Q. Xia, and A. L. Ruoff. High-pressure structure of gallium nitride: Wurtzite-to-rocksalt phase transition. Phys. Rev. B, 47: 12925-12928, 1993.
[8] M. Yoshida, A. Onodera, M. Ueno, K. Takemura, and O. Shimomura. Pressure-induced phase transition in SiC. Phys. Rev. B, 48: 10587-10590, 1993.
[9] T. Sekine and T. Kobayashi, ibid. 55, 8034 (1997).
[10] A. N. Mariano and E. P. Warekois. High Pressure Phases of Some Compounds of Groups Ⅱ-Ⅵ. Science, 142: 672-675, 1963.
[11] J. N. Wickham, A. B. Herhold, and A. P. Alivisatos. Shape Change as an Indicator of Mechanism in the High-Pressure Structural Transformations of CdSe Nanocrystals. Phys. Rev. Lett., 84: 923-926, 2000.
[12] M. D. Knudson, Y. M. Gupta, and A. B. Kunz. Transformation mechanism for the pressure-induced phase transition in shocked CdS. Phys. Rev. B 59: 11704-11715, 1999.
[13] S. Kodiyalam, R. K. Kalia, A. Nakano, and P. Vashishta. Multiple Grains in Nanocrystals: Effect of Initial Shape and Size on Transformed Structures Under Pressure. Phys. Rev. Lett., 93: 203401-203404, 2004.
[14] B. J. Morgan, and P. A. Madden. Pressure-Driven Sphalerite to Rock Salt Transition in Ionic Nanocrystals: A Simulation Study. Nano Lett., 4: 1581-1585, 2004.
[15] D. Zahn, Y. Grin, and S. Leoni. Mechanism of the pressure-induced wurtzite to rocksalt transition of CdSe. Phys. Rev. B, 72: 064110(7), 2005.
[16] S. Limpijumnong and W. R. L. Lambrecht. Homogeneous Strain Deformation Path for the Wurtzite to Rocksalt High-Pressure Phase Transition in GaN. Phys. Rev. Lett., 86: 91-94, 2001.
[17] N. J. Lee, R. K. Kalia, A. Nakano, and P. Vashishta. Pressure-induced struc-tural transformations in cadmium selenide nanorods. Appl. Phys. Lett., 89: 093101-093103, 2006.
[18] S. Limpijumnong and S. Jungthawan. First-principles study of the wurtzite-to-rocksalt homogeneous transformation in ZnO: A case of a low-transformation barrier. Phys. Rev. B, 70: 054104-054107, 2004.
[19] M. S. Miao and Walter R. L. Lambrecht. Unified path for high-pressure transitions of SiC polytypes to the rocksalt structure. Phys. Rev. B, 68: 092103-092106, 2003.
[20] C. Molteni, R. Martonak, M. Parrinello. First principles molecular dynamics simulations of pressure-induced structural transformations in silicon clusters. J. Chem. Phys., 114: 5358-5365, 2001.
[21] M. Ueno, M. Yoshida, A. Onodera, O. Shimomura, and K. Takemura. Stability of the wurtzite-type structure under high pressure: CaN and InN. Phys. Rev. B, 49: 14-21, 1994.
[22] M. Ueno, A. Onodera, O. Shimomura, and K. Takemura. X-ray observation of the structural phase transition of aluminum nitride under high pressure. Phys. Rev. B, 45: 10123-10126, 1992.
[23] P. Perlin, C. Jauberthie-Carillon, J. P. Itie, A. San Miguel, I. Grzegory, and A. Polian. High pressure phase transition in gallium nitride. High Press. Res., 71: 96-98, 1991.
[24] P. Perlin, I. Gorczyca, S. Porowski, T. Suski, N. E. Christensen, and A. Polian. Ⅲ-Ⅴ Semiconducting Nitrides: Physical Properties under Pressure. Jpn. J. Appl. Phys., Suppl., 32: 334-339, 1993.
[25] S. Uehara, T. Masamoto, A. Onodera, M. Ueno, O. Shimomura, and K. Takemura. Equation of state of the rocksalt phase of Ⅲ-Ⅴ nitrides to 72 GPa or higher. J. Phys. Chem. Solids, 58: 2093-2099, 1997.
[26] N. E. Christensen and I. Gorezyca. Optical and structural properties of Ⅲ-Ⅴ nitrides under pressure. Phys. Rev. B, 50: 4397-4415, 1994.
[27] A. Munoz and K. Kunc. High-pressure phase of gallium nitride. Phys. Rev. B, 44: 10372-10373, 1991.
[28] B. B. Karki and R. M. Wentzcovitch. Vibrational and quasiharmonic thermal properties of CaO under pressure. Phys. Rev. B, 68: 224304(6), 2003.
[29] H. Zhang, B. Gilbert, F. Huang, and J. F. Banfield. Water-driven structure transformation in nanoparticles at room temperature. Nature,(London)424: 1025-1029, 2003.
[30] S. Vemparala, R. K. Kalia, A. Nakano, and P. Vashishta. Electric field induced switching of poly(ethylene glycol) terminated self-assembled monolayers: A parallel molecular dynamics simulation. J. Chem. Phys., 121: 5427-5433, 2004.
[31] S. H. Tolbert and A. P. Alivisatos. The wurtzite to rock salt structural transformation in CdSe nanocrystals under high pressure. J. Chem. Phys., 102: 4642-4656, 1995.
[32] C.-C. Chen, A. B. Herhold, C. S. Johnson, and A. P. Alivisatos. Size Dependence of Structural Metastability in Semiconductor Nanocrystals. Science, 276: 398-401, 1997.
[33] K. Jacobs, D. Zaziski, E. C. Scher, A. B. Herhold, and A. P. Alivisatos. Activation Volumes for Solid-Solid Transformations in Nanocrystals. Science, 293: 1803-1806, 2001.
[34] K. Jacobs, J. Wickham, and A. P. Alivisatos. Threshold Size for Ambient Metastability of Rocksalt CdSe Nanocrystals. J. Phys. Chem. B, 106: 3759-3762, 2002.
[35] D. Zaziski, S. Prilliman, E. C. Scher, M. Casula, J. Wickham, S. M. Clark, and A. P. Alivisatos. Critical Size for Fracture during Solid-Solid Phase Transformations. Nano Lett., 4: 943-946, 2004.
[36] Michael Grunwald, Eran Rabani, and and Christoph Dellago. Mechanisms of the Wurtzite to Rocksalt Transformation in CdSe Nanocrystals. Phys. Rev. Lett., 96: 255701-255704, 2006.
[37] S. M. Sharma and Y. M. Gupta. Wurtzite-to-rocksalt structural transfor-mation in cadmium sulphide shocked along the a axis. Phys. Rev. B, 58: 5964-5971, 1998.
[38] S. Limpijumnong and W. R. L. Lambrecht. Theoretical study of the relative stability of wurtzite and rocksalt phases in MgO and GaN. Phys. Rev. B, 63: 104103(11), 2001.
[39] H. Sowa, Acta Crystallogr., Sect. A: Found. Crystallogr. On the transition from the wurtzite to the NaCl type. 57: 176-182, 2001.
[40] M. Wilson and P. A. Madden. Transformations between tetrahedrally and octahedrally coordinated crystals: the wurtzite to rocksalt and blende to rocksalt mechanisms. J. Phys.: Condens. Matter, 14: 4629-4643, 2002.
[41] C. B. Barber, D. P. Dobkin, and H. Huhdanpaa, ACM Trans. Math. Softw. 22, 469 (1996).
[42] E. Rabani. An interatomic pair potential for cadmium selenide. J. Chem. Phys., 116: 258-262, 2002.
[43] E. Rabani. Structure and electrostatic properties of passivated CdSe nanocrystals. J. Chem. Phys. 115: 1493-1497, 2001.
[44] S. Kodiyalam, R. K. Kalia H. Kikuchi, A. Nakano, F. Shimojo, and P. Vashishta. Grain Boundaries in Gallium Arsenide Nanocrystals Under Pressure: A Parallel Molecular-Dynamics Study. Phys. Rev. Lett., 86: 55-58, 2001.
[45] A. J. Kulkarni, M. Zhou, K. Sarasamak, and S. Limpijumnong. Novel Phase Transformation in ZnO Nanowires under Tensile Loading. Phys. Rev. Lett., 97: 105502-105505, 2006.