title: A density-based adaptive quantum mechanical/molecular mechanical method.
abstract: We present a density-based adaptive quantum mechanical/molecular mechanical (DBA-QM/MM) method, whereby molecules can switch layers from the QM to the MM region and vice versa. The adaptive partitioning of the molecular system ensures that the layer assignment can change during the optimization procedure, that is, on the fly. The switch from a QM molecule to a MM molecule is determined if there is an absence of noncovalent interactions to any atom of the QM core region. The presence/absence of noncovalent interactions is determined by analysis of the reduced density gradient. Therefore, the location of the QM/MM boundary is based on physical arguments, and this neatly removes some empiricism inherent in previous adaptive QM/MM partitioning schemes. The DBA-QM/MM method is validated by using a water-in-water setup and an explicitly solvated L-alanyl-L-alanine dipeptide.
authors: Theoretische Organische Chemie, Organisch-Chemisches, Institut and Center for Multiscale Theory and Computation, Westfalische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster (Germany), Fax: (+49) 0251 83 33202. m.waller@uni-muenster.de.
authors: Mark P
authors: MP
authors: Waller
authors: Sadhana
authors: S
authors: Kumbhar
authors: Jack
authors: J
authors: Yang
keywords: adaptive; molecular modeling; noncovalent interactions; quantum chemistry; topology