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Title: Perturbative approximation to hybrid equation of motion coupled cluster/effective fragment potential method

Hybrid quantum mechanics/molecular mechanics (QM/MM) methods provide an attractive way to closely retain the accuracy of the QM method with the favorable computational scaling of the MM method. Therefore, it is not surprising that QM/MM methods are being increasingly used for large chemical/biological systems. Hybrid equation of motion coupled cluster singles doubles/effective fragment potential (EOM-CCSD/EFP) methods have been developed over the last few years to understand the effect of solvents and other condensed phases on the electronic spectra of chromophores. However, the computational cost of this approach is still dominated by the steep scaling of the EOM-CCSD method. In this work, we propose and implement perturbative approximations to the EOM-CCSD method in this hybrid scheme to reduce the cost of EOM-CCSD/EFP. The timings and accuracy of this hybrid approach is tested for calculation of ionization energies, excitation energies, and electron affinities of microsolvated nucleic acid bases (thymine and cytosine), phenol, and phenolate.
Authors:
 [1]
  1. Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008 (India)
Publication Date:
OSTI Identifier:
22255015
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ACCURACY; AFFINITY; APPROXIMATIONS; CYTOSINE; EQUATIONS OF MOTION; HYBRIDIZATION; NUCLEIC ACIDS; PHENOL; PHENOLATES; QUANTUM MECHANICS; SOLVENTS; SPECTRA; THYMINE