UNIFIED APPROACH FOR THE CALCULATION OF FORCE-CONSTANTS AND ACCELERATED CONVERGENCE OF ATOMIC COORDINATES

A method which simultaneously computes the force-constant matrix (FCM) and relaxes the atomic coordinates to the ground state of a generic s ystem is introduced. The method is based on the optimization of the FC M as the atomic coordinates evolve to their ground-stare configuration , using the variations in atomic positions and forces from previous it erations as inputs. Striking accelerated convergence as compared to tr aditional methods is obtained, as well as accurate vibrational frequen cies with no additional cost.