Calculation of bromine nuclear quadrupole coupling constants in gaseous state molecules

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Conference Proceeding

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Several DFr and hybrid HF/DFT methods in conjunction with Pople (6-311G) and Ahlrichs (TZV) bases have been investigated for the calculation of 79Br and 81Br nuclear quadrupole coupling constants (nqccs) in gaseous state molecules. The molecules are HBr, BrF, BrCl, Br2, BrCN, BrBO, HCCBr, CH3Br, CH2Br2, CF3Br, CH2CHBr, and CH3CH2Br. Assessment of the various models was made by linear regression analysis of calculated electric fields versus experimental nqccs. The best results are obtained with the B1LYP, B3LYP, and LG1LYP hybrid methods combined with Ahlrichs' TZV bases plus polarization. With the B1LYP/TZV(3df, 3p) model, for example, the residual standard deviation for 79Br is 1.7 MHz (0.42%), and for 81Br, 1.5 MHz (0.42%). The effective nuclear electric quadrupole moments derived from the slopes of the regression lines are, respectively, 330.4 and 276.0 mb. This B1LYP model is applied to calculation of the 79Br nqccs in SiF3Br and SiH3Br for the purpose of investigation of the SiBr bond lengths. © 2003 Elsevier Science B,V. All rights reserved.

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Journal of Molecular Structure

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