STUDY ON IMPROVING THE ACCURACY OF THE TOTAL-ENERGY CALCULATED BY THEDV-X-ALPHA METHOD

The effect of the truncation errors resulting from the numerical integ ration on the accuracy of the calculation results in the DV-X alpha me thod is analyzed and it is shown that evaluating the overlap integrals analytically or adopting orthogonalized basis sets can reduce the err ors on the density matrices to the second order. An approach to improv e the calculation accuracy of the total energy is proposed based on th e error analysis. The calculation results for several molecules are pr esented to demonstrate the conclusion. (C) 1994 John Wiley and Sons, I nc.