Short- and long-range potential functions for valence-bonded crystals using valence symmetry coordinates
The theory is given for deriving symmetry coordinates suited to calculating correct normal modes as well as vibration frequencies in crystals. In addition, the coordinates should be well suited to expressing force constants in terms of the energy changes accompanying distortion of the ground-state electron configuration. The coordinates are chosen as symmetrical displacement patterns of the atoms in a primitive cell and adjacent cells. They can be chosen to emphasize stretching of bonds or deformations of interbond angles and, therefore, to take account of valence bonding in the crystal. The long-range- force interactions arising from vibrationally induced dipoles are conveniently expressed. To illustrate the method an application to diamond is developed. (auth)
- Research Organization:
- Aerojet Nuclear Co., Idaho Falls, Idaho (USA)
- DOE Contract Number:
- AT(10-1)-1375
- NSA Number:
- NSA-29-009655
- OSTI ID:
- 4412349
- Report Number(s):
- ANCR--1126
- Country of Publication:
- United States
- Language:
- English
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