FORMULAS FOR THE 1ST AND 2ND DERIVATIVES OF ANISOTROPIC POTENTIALS WITH RESPECT TO GEOMETRICAL PARAMETERS

We have derived formulae for the forces and torques arising from the electrostatic energy of a system of rigid molecules, using a rigorous unified approach. We have also obtained systematically the second derivatives with respect to translational and rotational coordinates. Some of the properties of first and second derivatives are discussed for the general case of a system with arbitrary symmetry. Derivatives of a general anisotropic exponential repulsive potential have also been evaluated. All of these have been implemented as Fortran subroutines in the Orient program.