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Analytic first and second derivatives of the energy in the fragment molecular orbital method combined with molecular mechanics
Author(s) -
Nakata Hiroya,
Fedorov Dmitri G.
Publication year - 2020
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.26414
Subject(s) - fragment molecular orbital , molecular mechanics , molecular orbital , molecular dynamics , embedding , force field (fiction) , chemistry , computational chemistry , fragment (logic) , density functional theory , ionic bonding , molecular physics , chemical physics , physics , molecule , quantum mechanics , ion , mathematics , algorithm , artificial intelligence , computer science
Analytic first and second derivatives of the energy are developed for the fragment molecular orbital method interfaced with molecular mechanics in the electrostatic embedding scheme at the level of Hartree‐Fock and density functional theory. The importance of the orbital response terms is demonstrated. The role of electrostatic embedding upon molecular vibrations is analyzed, comparing force field and quantum mechanical treatments for an ionic liquid and a solvated protein. The method is applied for 100 protein conformations sampled in molecular dynamics (MD) to take into account the complexity of a flexible protein structure in solution, and a good agreement with experimental data is obtained: Frequencies from an experimental infrared (IR) spectrum are reproduced within 17 cm −1 .