Transferability of Atomic Multipoles in Amino Acids and Peptides for Various Density Partitions
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- 作者：Magdalena Woi艅ska ; Paulina M. Dominiak
- 刊名：The Journal of Physical Chemistry A
- 出版年：2013
- 出版时间：February 21, 2013
- 年：2013
- 卷：117
- 期：7
- 页码：1535-1547
- 全文大小：867K
- 年卷期：v.117,no.7(February 21, 2013)
- ISSN：1520-5215
文摘
Multipole expansion of electron density distribution is an efficient tool for evaluating the energy of interactions in molecules. In as much as atoms in macromolecules such as peptides are modeled with certain types of atoms derived from small organic molecules, investigating transferability of atomic multipoles for various partitions of molecular electron density is an important issue. In this study, multipole moments up to hexadecapoles for types of atoms present in selected amino acids, as well as di- and tripeptides composed of these amino acids, are computed using three density partitions: Hansen-Coppens aspherical pseudoatoms formalism, Hirshfeld鈥檚 stockholder partition, and Bader鈥檚 atoms in molecules theory. Electron density of relevant molecules is derived in a procedure including molecular wave function ab initio calculation for isolated molecules in geometry from X-ray measurements, calculation of theoretical structure factors for molecules put in a pseudocubic cell, and multipole refinement as in crystallographic data processing and computation of multipoles. The results were compared to calculations of multipole moments in AIM and in stockholder density partitions obtained directly from molecular wave functions. The presented comparison does not point unambiguously to any particular influence of multipole refinement on moments obtained from these two partitions. The advantage of stockholder partitioning in terms of transferability of atomic multipoles is affirmed. AIM and pseudoatoms provide slightly less transferable multipoles of lower order. Higher rank of multipole expansion reveals a transferability improvement in the case of AIM and meaningful deterioration for pseudoatoms.