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Evaluation of optical activities by modern semi‐empirical methods
Author(s) -
Hatanaka Masashi
Publication year - 2013
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.24478
Subject(s) - cndo/2 , mndo , chemistry , optical rotatory dispersion , dipole , molecular orbital , spectral line , wave function , circular dichroism , molecule , oscillator strength , computational chemistry , molecular physics , crystallography , atomic physics , physics , quantum mechanics , organic chemistry
Modern semi‐empirical molecular orbital methods are applied herein to the direct calculation of the optical rotatory strengths of model molecules. In addition to MNDO, AM1, and PM3 methods, RM1, PM6, and PM7 wavefunctions are used for evaluation of the dipole transition moments. The octant rule for carbonyl compounds is well‐adhered to using the RM1, PM6, and PM7 methods and is reasonably consistent with the charge‐transfer perturbations with regard to the substituents. By using the up‐to‐date methods RM1 and PM7, circular dichroism (CD) spectra of a typical helicene are also well‐reproduced using complete active space configuration interactions. The CD spectral profiles are significantly improved relative to those obtained using conventional CNDO/S or INDO/S levels of theory and are complemented by optical rotatory dispersion spectra. As a platform for analyzing biopolymers, test calculations for polypeptides are also presented. © 2013 Wiley Periodicals, Inc.