An implementation of the conductor-like screening model of solvation within the Amsterdam density functional package

The conductor-lilte screening model (COSMO) of solvation has been implemented in the Amsterdam density functional program with maximum flexibility in mind. Four cavity definitions have been incorporated. Several iterative schemes have been tested for solving the COSMO equations. The biconjugate gradient method proves to be both robust and memory-conserving, The interaction between the surface charges and the electron density may be calculated by integrating over either the fitted or exact density, or by calculating the molecular potential. A disk-smearing algorithm is applied in the former case to avoid singularities. Several self-consistent field/COSMO coupling schemes were examined in an attempt to reduce computational effort. A gradient-preserving algorithm for removing outlying charge has been implemented. Preliminary optimized radii are given. Applications to the benzene oxide-oxepin valence tautomerization and to glycine conformation are presented.