We have compared four approximations to the function gKL (R) =(ϕK|∂/∂R|ϕL): 1) The finite differences derivation formulas. 2) The approximation of neglecting the variation of the MO's with respect to that of the CI coefficients. 3) The Hellmann—Feynman formula 4) The Sidis formula for diatomics As previously shown, method A gives satisfying results, but requires to compute the electronic wavefunctions at two neighbouring geometries at least. The main purpose of this work is to test the accuracy of cheaper methods, through an application to the X—A 1Σ+ states of LiH, and to discuss their physical meaning.
The evaluation of non adiabatic matrix elements. A comparison of different approximations applied to LiH X-A ^1\Sigma^+
CIMIRAGLIA, Renzo;
1980
Abstract
We have compared four approximations to the function gKL (R) =(ϕK|∂/∂R|ϕL): 1) The finite differences derivation formulas. 2) The approximation of neglecting the variation of the MO's with respect to that of the CI coefficients. 3) The Hellmann—Feynman formula 4) The Sidis formula for diatomics As previously shown, method A gives satisfying results, but requires to compute the electronic wavefunctions at two neighbouring geometries at least. The main purpose of this work is to test the accuracy of cheaper methods, through an application to the X—A 1Σ+ states of LiH, and to discuss their physical meaning.File in questo prodotto:
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