Novel SCS-IL-MP2 and SOS-IL-MP2 methods for accurate energetics of large-scale ionic liquid clusters

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Abstract

Accurate energetics of intermolecular interactions in condensed systems are challenging to predict using highly correlated quantum chemical methods due to their great computational expense. Semi-Coulomb systems such as ionic liquids, in which electrostatic, dispersion, and induction forces are equally important, represent a further challenge for wave function-based methods. Here, the application of our recently developed SCS-IL-MP2 and SOS-IL-MP2 methods is reported for ionic liquid clusters of two and four ion pairs. Correlation interaction energies were found to be within 1.5 kJ mol-1, on average, per ion pair of the CCSD(T)/CBS benchmark, thus introducing a marked improvement by a factor of 4 to conventional MP2 within the complete basis set. The fragment molecular orbital (FMO) approach in combination with both SCS-IL-MP2 and SOS-IL-MP2 has been shown to provide a reliable and computationally inexpensive alternative to CCSD(T)/CBS for large-scale calculations of ionic liquids, thus paving the way toward feasible ab initio molecular dynamics and development of reliable force fields for these condensed systems
Original languageEnglish
Pages (from-to)3610-3616
Number of pages7
JournalJournal of Chemical Theory and Computation
Volume11
Issue number8
DOIs
Publication statusPublished - 2015

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