LARGE-SCALE RANDOM PHASE CALCULATIONS FOR DIRECT SELF-CONSISTENT FIELD WAVE-FUNCTIONS

We present an implementation of the double-direct random phase approxi mation (DDRPA) method for closed-shell and one-open-shell systems. The method is termed double-direct since (1) it is driven directly by the atomic orbital integrals, and since (2) it uses iterative techniques based on direct linear transformations for solving the RPA eigenvalue equations and sets of linear equations. The method can be used for cal culating linear response properties such as polarizabilities and excit ation spectra of large species. We demonstrate its potential by calcul ating excitation energies and transition moments as well as static and dynamic polarizabilities of para-nitroaniline.