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On the suitability of strictly localized orbitals for hybrid QM/MM calculations
Author(s) -
Fornili Arianna,
Moreau Yohann,
Sironi Maurizio,
Assfeld Xavier
Publication year - 2006
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20366
Subject(s) - localized molecular orbitals , atomic orbital , molecular orbital , chemistry , molecule , natural bond orbital , orbital overlap , computational chemistry , orbital hybridisation , chemical physics , chemical bond , molecular physics , atomic physics , physics , molecular orbital theory , density functional theory , quantum mechanics , electron , organic chemistry
In the QM/MM method we have developed (LSCF/MM), the QM and the MM parts are held together by means of strictly localized bonding orbitals (SLBOs). Generally these SLBOs are derived from localized bond orbitals (LBOs) that undergo tails deletion, resulting in a nonpredictable change of their properties. An alternative set of SLBOs is provided by the extremely localized molecular orbitals (ELMOs) approach, where the orbitals are rigorously localized on some prefixed atoms without tails on the other atoms of the molecule. A comparative study of SLBOs arising from various localization schemes and ELMOs is presented to test the reliability and the transferability of these functions within the Local Self‐Consistent Field (LSCF) framework. Two types of chemical bonds were considered: CC and CO single bonds. The localized functions are obtained on the ethane and the methanol molecules, and are tested on β‐alanine and diethyl ether molecules. Moreover, the various protonation forms of β‐alanine have been investigated to illustrate how well the polarity variation of the chemical bond can be handled throughout a chemical process. At last, rotation energy profiles around CC and CO bonds are reproduced for butane and fluoromethanol. Energetic, geometric, as well as electronic factors all indicate that ELMO functions are much more transferable from one molecule to another, leading to results closer to the usual SCF reference than any other calculations involving any other localized orbitals. When the shape of the orbital is the most important factor then ELMO functions will perform as well as any other localized orbital. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 515–523, 2006