THE DEFINITION OF REACTION COORDINATES FOR REACTION-PATH DYNAMICS

被引:137
作者
NATANSON, GA
GARRETT, BC
TRUONG, TN
JOSEPH, T
TRUHLAR, DG
机构
[1] PACIFIC NW LAB, MOLEC SCI RES CTR, RICHLAND, WA 99352 USA
[2] UNIV MINNESOTA, DEPT CHEM, MINNEAPOLIS, MN 55455 USA
[3] UNIV MINNESOTA, INST SUPERCOMP, MINNEAPOLIS, MN 55455 USA
关键词
D O I
10.1063/1.460123
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
We present equations for generalized-normal-mode vibrational frequencies in reaction-path calculations based on various sets of coordinates for describing the internal motions of the system in the vicinity of a reaction path. We consider two special cases in detail as examples, in particular three-dimensional atom-diatom collisions with collinear steepest descent paths and reactions of the form CX3 + YZ --> CX3Y + Z with reaction paths having C3-upsilon symmetry. We then present numerical comparisons of the differences in harmonic reaction-path frequencies for various coordinate choices for three such systems, namely, H + H-2 --> H-2 + H, O + H-2 --> OH + H, and CH3 + H-2 --> CH4 + H. We test the importance of the differences in the harmonic frequencies for dynamics calculations by using them to compute thermal rate constants using variational transition state theory with semiclassical ground-state tunneling corrections. We present a new coordinate system for the reaction CH3 + H-2 that should allow for more accurate calculations than the Cartesian system used for previous reaction-path calculations on this and other polyatomic systems.
引用
收藏
页码:7875 / 7892
页数:18
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