Minimization programs for potential energy calculations in crystals and isolated molecules and macromolecules.

Potential-energy calcns. by a simple grid-point method were made to solve the phase problem in crystals and to predict the more stable conformations of mols. and macromols. To save computing time, 2 minimization programs were written that explore the min. regions. The potential energy can be computed by taking into account van der Waals, torsional, H-bond, and monopole interactions. In the 1st program, the asym. unit, treated as a rigid body, is moved in the crystal as a function of the 3 rotational and 3 translational degrees of freedom. In the 2nd, any no. of degrees of freedom can be handled, in theory, for a single mol. or macromol., and the equivalence principle can be applied to a polymer. Some examples and implications of the programs are discussed.