Analytical First and Second Derivatives for a Fully Polarizable QM/Classical Hamiltonian.

In this work, we present the derivation and implementation of analytical first and second derivatives for a fully polarizable QM/MM/PCM energy functional. First derivatives with respect to both QM- and MM-described nuclear coordinates and electric perturbations are derived and implemented, and some preliminary application is shown. Analytical second derivatives with respect to nuclear and electric perturbations are then derived, and some numerical test is presented both for a solvated system and for a cromophore embedded in a biological matrix.