Optimizing Vibrational Coordinates To Modulate Intermode Coupling.

摘要: The choice of coordinate system strongly affects the convergence properties vibrational structure computations. Two methods for efficient generation improved coordinates are presented and justified by analysis a model anharmonic two-mode Hessian numerical computations on polyatomic molecules. To produce optimal coordinates, metrics which quantify off-diagonal couplings over grid matrices minimized through unitary rotations basis. first proposed metric minimizes total squared coupling, second change in coupling. In this procedure certain modes tend to localize, example X–H stretches. do not rely prior fitting potential energy, computations, or localization metrics, so they unique from previous algorithms generally applicable Fitting pote...