Time-dependent variational principle for nonlinear Hamiltonians and its application to molecules in the liquid phase

Abstract

The formulation of the time-dependent Frenkel variational principle for Hamiltonians containing a term depending on the wave function is here considered. Starting from the basic principles, it is shown that it requires the introduction of a related functional, G, which, for the systems we are considering, has the status of a free energy. An explicit use of functional G as starting point to obtain variational wave functions makes it easier to implement computational methods for a variety of physical and chemical problems in solution, the first one among them being the calculation of frequency-dependent nonlinear optical properties of components of the liquid phase. A concise overview of applications of this approach which are presently being worked out in our laboratory is also given. © 1996 John Wiley & Sons, Inc.