ISSN:
0020-7608
Keywords:
Chemistry
;
Theoretical, Physical and Computational Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The correlation between intramolecular bond length and vibrational frequency shifts was calculated at the MP4(aug-cc-PVTZ) ab initio level for a number of molecules (LiH, BH, HF, OH-, HDO, BF, CN-, and HCI) exposed to uniform electric fields in the range from -0.10 to +0.10 au. The “ω vs. re” correlation curves always consist of two branches, each approximately linear. The slopes for the molecules investigated here vary between -2500 and -16600 cm-1/Å. The slopes are well described by an expression containing only the free-molecule second- and third-order force constants and the reduced mass for the stretching mode. Experimental data for polar molecules can be expected to show deviations from a linear “ω vs. re” correlation (i) for molecules where the maximum of the frequency vs. field curve occurs at a positive field and (ii) for molecules where the maximum of the frequency vs. field curve falls on the negative-field side but very close to the zero-field case, and (iii) in bonding situations when there is much electron overlap. As opposed to uniform-field situations, anharmonicity and electronic overlap have a substantial influence on the “frequency vs. re” slopes in molecular environments. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 537-546, 1997
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
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