VSCF in internal coordinates and the calculation of anharmonic torsional mode transitions

被引：18
作者：
Suwan, Iyad [1 ,2 ]
Gerber, R. B. [1 ,2 ,3 ]
机构：
[1] Hebrew Univ Jerusalem, Inst Chem, IL-91904 Jerusalem, Israel
[2] Hebrew Univ Jerusalem, Fritz Haber Res Ctr, IL-91904 Jerusalem, Israel
[3] Univ Calif Irvine, Dept Chem, Irvine, CA 92797 USA
来源：
CHEMICAL PHYSICS | 2010年 / 373卷 / 03期
关键词：
VSCF; Internal coordinates; Anharmonic; Torsion; SELF-CONSISTENT-FIELD; INITIAL-VALUE REPRESENTATION; AB-INITIO; VIBRATIONAL SPECTROSCOPY; POLYATOMIC-MOLECULES; POTENTIAL SURFACES; QUANTUM-MECHANICS; WAVE-FUNCTIONS; MONTE-CARLO; STATES;
D O I：
10.1016/j.chemphys.2010.05.025
中图分类号：
O64 [物理化学（理论化学）、化学物理学];
学科分类号：
070304 ; 081704 ;
摘要：
The vibrational self-consistent field (VSCF) method assumes separability in normal modes in its usual version. However, the method fails in cases such as soft torsional modes which are better treated by angular variables. We develop VSCF equations based on the assumption of wave function separability in internal coordinates. To test the method, simple illustrative applications to small systems are provided: trans-HONO, cis-HONO, H2S2, and H2O2. The code directly uses points from ab initio calculations, and the method proves to be accurate for all types of transitions. For typical torsional transitions, the error in the computed frequency is smaller than that of VSCF in normal coordinates. The wave functions for the torsional mode are compared with the corresponding normal mode wave functions. The differences are substantial. The results are encouraging for extension of the model for large polyatomic systems. Work along these lines is in progress. (C) 2010 Elsevier B. V. All rights reserved.
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收藏
页码：267 / 273
页数：7
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