Molecules-in-Molecules: An Extrapolated Fragment-Based Approach for Accurate Calculations on Large Molecules and Materials

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• 作者：Nicholas J. Mayhall ; Krishnan Raghavachari
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2011
• 出版时间：May 10, 2011
• 年：2011
• 卷：7
• 期：5
• 页码：1336-1343
• 全文大小：883K
• 年卷期：v.7,no.5(May 10, 2011)
• ISSN：1549-9626

文摘

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.