DETERMINATION OF VIBRATIONAL FORCE FIELDS IN POLYATOMIC MOLECULES AND AN APPLICATION TO THE DEUTEROETHANES
A method is given to find the vibrational force field for a family of molecules. Partial derivatives of characteristic frequencies with respect to force constants are calculated. These partial derivatives remain nearly constant for small changes in the assumed force field. A least squares procedure gives a refined force field to obtain the best fit between calculated and observed frequencies. The constraints imposed on the general force field by redundant coordinates are discussed. Redundancy conditions for certain carbon- containing groups are calculated explicitly. An application is made to the isotopic ethanes. The general quadratic force field of twenty-two independent constants is determined by fitting calculated frequencies to 128 observed frequencies assigned from ten isotopic varieties, and experimental results are reproduced with a 1.1 per cent standard deviation. Characteristic frequencies are predicted for the four remaining deuteroethanes.
- Research Organization:
- Univ. of North Carolina, Chapel Hill
- NSA Number:
- NSA-16-024300
- OSTI ID:
- 4805563
- Journal Information:
- Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 22
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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