Schmidt J R, Corcelli S A, Skinner J L
Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Chem Phys. 2004 Nov 8;121(18):8887-96. doi: 10.1063/1.1791632.
Kwac and Cho [J. Chem. Phys. 119, 2247 (2003)] have recently developed a combined electronic structure/molecular dynamics approach to vibrational spectroscopy in liquids. The method involves fitting ab initio vibrational frequencies for a solute in a cluster of solvent molecules to a linear combination of the electrostatic potentials on the solute atoms due to the charges on the solvent molecules. These authors applied their method to the N-methylacetamide-D/D(2)O system. We (S. A. Corcelli, C. P. Lawrence, and J. L. Skinner, [J. Chem. Phys. 120, 8107 (2004)]) have recently explored a closely related method, where instead of the electrostatic potential, the solute vibrational frequencies are fit to the components of the electric fields on the solute atoms due to the solvent molecules. We applied our method to the HOD/D(2)O and HOD/H(2)O systems. In order to make a direct comparison of these two approaches, in this paper we apply their method to the water system, and our method to the N-methylacetamide system. For the water system we find that the electric field method is superior to the potential approach, as judged by comparison with experiments for the absorption line shape. For the N-methylacetamide system the two methods are comparable.
夸克和赵[《化学物理杂志》119, 2247 (2003)]最近开发了一种结合电子结构/分子动力学的方法来研究液体中的振动光谱。该方法包括将溶剂分子簇中溶质的从头算振动频率拟合为溶质原子上由于溶剂分子电荷产生的静电势的线性组合。这些作者将他们的方法应用于N - 甲基乙酰胺 - D/D₂O体系。我们（S. A. 科尔塞利、C. P. 劳伦斯和J. L. 斯金纳，[《化学物理杂志》120, 8107 (2004)]）最近探索了一种密切相关的方法，其中溶质振动频率不是拟合为静电势，而是拟合为由于溶剂分子在溶质原子上产生的电场分量。我们将我们的方法应用于HOD/D₂O和HOD/H₂O体系。为了对这两种方法进行直接比较，在本文中我们将他们的方法应用于水体系，将我们的方法应用于N - 甲基乙酰胺体系。对于水体系，通过与吸收线形状的实验比较判断，我们发现电场方法优于电势方法。对于N - 甲基乙酰胺体系，这两种方法相当。
