TY - JOUR
T1 - A QM/MM study on the correlation between the polarisations of π and σ electrons in a hydrated benzene
AU - Suzuoka, Daiki
AU - Takahashi, Hideaki
AU - Morita, Akihiro
N1 - Funding Information:
This work is supported by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) under the Grant-in-Aid for Scientific Research on Innovative Areas [grant number 23118701]; the Japan Society for the Promotion of Science (JSPS) under the Grant-in-Aid for Challenging Exploratory Research [grant number 25620004]; the Nanoscience Program and the Computational Materials Science Initiative of the Next-Generation Supercomputing Project (No. hp160007, hp160013, hp160019 and hp160214); JSPS Research Fellowships for Young Scientists [grant number JP16J02027].
Publisher Copyright:
© 2017 Informa UK Limited, trading as Taylor & Francis Group.
PY - 2017
Y1 - 2017
N2 - In a recent work, we performed free-energy analyses for hydration of benzene by conducting QM/MM-ER simulations, where the total solvation free energy Δμ was decomposed into contributions Δμ and δμ (Δμ = Δμ + δμ). Δμ is the solvation free energy of the solute with a fixed electron density and δμ is the residual free energy due to the electron density polarisation in solution. We, further, decomposed the free energies δμ due to electron density fluctuations in aromatic solutes in aqueous solutions into contributions from π and σ orbitals. We note, however, that the decompositions will not be validated when the polarisations of π orbitals seriously couple with those of σ orbitals. In this paper, we study a correlation matrix between polarisations of π and σ orbitals through QM/MM simulations to assess the coupling strength among the orbitals. We found that the electron density polarisation is dominated by the polarisation arising from π - π * transfers between the orbitals lying in the HOMO-LUMO region. Thus, the polarisation of π electrons hardly couples with that from σ orbitals, which justifies our decomposition analyses.
AB - In a recent work, we performed free-energy analyses for hydration of benzene by conducting QM/MM-ER simulations, where the total solvation free energy Δμ was decomposed into contributions Δμ and δμ (Δμ = Δμ + δμ). Δμ is the solvation free energy of the solute with a fixed electron density and δμ is the residual free energy due to the electron density polarisation in solution. We, further, decomposed the free energies δμ due to electron density fluctuations in aromatic solutes in aqueous solutions into contributions from π and σ orbitals. We note, however, that the decompositions will not be validated when the polarisations of π orbitals seriously couple with those of σ orbitals. In this paper, we study a correlation matrix between polarisations of π and σ orbitals through QM/MM simulations to assess the coupling strength among the orbitals. We found that the electron density polarisation is dominated by the polarisation arising from π - π * transfers between the orbitals lying in the HOMO-LUMO region. Thus, the polarisation of π electrons hardly couples with that from σ orbitals, which justifies our decomposition analyses.
KW - Correlation matrix
KW - QM/MM-ER
KW - Second-order perturbation theory
KW - Solvation free energy
KW - XH/π interaction
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U2 - 10.1080/08927022.2017.1350661
DO - 10.1080/08927022.2017.1350661
M3 - Article
AN - SCOPUS:85025166957
VL - 43
SP - 1209
EP - 1217
JO - Molecular Simulation
JF - Molecular Simulation
SN - 0892-7022
IS - 13-16
ER -