title: Molecules-in-Molecules: An Extrapolated Fragment-Based Approach for Accurate Calculations on Large Molecules and Materials.
abstract: We present a new extrapolated fragment-based approach, termed molecules-in-molecules (MIM), for accurate energy calculations on large molecules. In this method, we use a multilevel partitioning approach coupled with electronic structure studies at multiple levels of theory to provide a hierarchical strategy for systematically improving the computed results. In particular, we use a generalized hybrid energy expression, similar in spirit to that in the popular ONIOM methodology, that can be combined easily with any fragmentation procedure. In the current work, we explore a MIM scheme which first partitions a molecule into nonoverlapping fragments and then recombines the interacting fragments to form overlapping subsystems. By including all interactions with a cheaper level of theory, the MIM approach is shown to significantly reduce the errors arising from a single level fragmentation procedure. We report the implementation of energies and gradients and the initial assessment of the MIM method using both biological and materials systems as test cases.
authors.affiliation: Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Mayhall
authors.affiliation: Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Raghavachari