Engineering topics

Wilkins, J. W.

Publications and source records attributed to Wilkins, J. W..

2 records

NASA NTRS1983

Band-overlap metallization of BaS, BaSe and BaTe

The insulator-metal transition volumes for BaS, BaSe, and BaTe are calculated for the first time, using the self-consistent augmented spherical wave technique. The metallized transition volumes are smaller than those corresponding to the NaCl yields CsCl structural transitions, but, 10 to 15% larger than those obtained by the Herzfeld dielectric theory. The calculated equilibrium energy gaps in the NaCl structure underestimate the measured ones by 50 to 60%.

Carlsson, A. E.↗

NASA NTRS1975

Four-particle exchange in solid He-3

Calculations are reported which suggest that there is a physically important four-atom exchange process in bcc He-3 and an important four-spin term in the exchange Hamiltonian. A simple mean-field analysis of this Hamiltonian appears to account for a number of the perplexing properties of bcc He-3. An understanding of other properties may require treatment of the exact four-spin term.

Mcmahan, A. K.↗