Vibrational Energy Relaxation of the Amide I Mode of N-Methylacetamide in D2O Studied through Born鈥揙ppenheimer Molecular Dynamics

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• 作者：Marwa H. Farag ; Adolfo Bastida ; Manuel F. Ruiz-L贸pez ; G茅rald Monard ; Francesca Ingrosso
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：June 12, 2014
• 年：2014
• 卷：118
• 期：23
• 页码：6186-6197
• 全文大小：482K
• 年卷期：v.118,no.23(June 12, 2014)
• ISSN：1520-5207

文摘

The vibrational relaxation of the amide I mode of deuterated N-methylacetamide in D₂O solution is studied through nonequilibrium simulations using the semiempirical Born鈥揙ppenheimer molecular dynamics (SEBOMD) approach to describe the whole solute鈥搒olvent system. Relaxation pathways and lifetimes are determined using the instantaneous normal mode (INM) analysis. The relaxation of the amide I mode is characterized by three different time scales; most of the excess energy (80%) is redistributed through intramolecular vibrational energy redistribution processes, with a smaller contribution (20%) of intermolecular energy flowing into the solvent. The amide II mode is found to contribute modestly (7%) to the relaxation mechanism. The amide I mode and the total vibrational energy decay curves obtained using SEBOMD and INM are in satisfactory agreement with the experimental measurements.