Minimal Basis Iterative Stockholder: Atoms in Molecules for ForceField Development
Abstract
Atomic partial charges appear in the Coulomb term of many forcefield models and can be derived from electronic structure calculations with a myriad of atomsinmolecules (AIM) methods. More advanced models have also been proposed, using the distributed nature of the electron cloud and atomic multipoles. In this work, an electrostatic force field is defined through a concise approximation of the electron density, for which the Coulomb interaction is trivially evaluated. This approximate "prodensity" is expanded in a minimal basis of atomcentered stype Slater density functions, whose parameters are optimized by minimizing the KullbackLeibler divergence of the prodensity from a reference electron density, e.g. obtained from an electronic structure calculation. The proposed method, Minimal Basis Iterative Stockholder (MBIS), is a variant of the Hirshfeld AIM method but it can also be used as a densityfitting technique. An iterative algorithm to refine the prodensity is easily implemented with a linearscaling computational cost, enabling applications to supramolecular systems. The benefits of the MBIS method are demonstrated with systematic applications to molecular databases and extended models of condensed phases. A comparison to 14 other AIM methods shows its effectiveness when modeling electrostatic interactions. MBIS is also suitable for rescaling atomic polarizabilities in the TkatchenkoSheffler scheme for dispersion interactions.
 Publication:

arXiv eprints
 Pub Date:
 August 2016
 arXiv:
 arXiv:1608.05556
 Bibcode:
 2016arXiv160805556V
 Keywords:

 Physics  Chemical Physics;
 Physics  Atomic and Molecular Clusters;
 Physics  Atomic Physics;
 Physics  Computational Physics;
 Quantum Physics
 EPrint:
 61 pages, 12 figures, 2 tables