1,721,026 research outputs found
PRESSURE DEPENDENCES OF BAND-GAPS AND OPTICAL-PHONON FREQUENCY IN CUBIC SIC
No full textThe high-pressure behavior of the direct and indirect band gaps in zinc-blende-structure SiC is examined with use of self-consistent ab initio pseudopotential calculations. The fundamental band gap from GAMMA-15-nu to X1c is found to decrease linearly with pressure up to 200 kbar. This result disagrees with a recent experimental finding of strong sublinear behavior at pressures of 10 to 15 kbar. The linear pressure coefficients of the fundamental band pp and the transverse-optical-phonon frequency at the GAMMA-point in the Brillouin zone are in good agreement with measured values
FIRST-PRINCIPLES CALCULATIONS OF THE COULOMB PSEUDOPOTENTIAL MU-ASTERISK - APPLICATION TO AL
No full textWe present first-principles pseudopotential calculations for the Coulomb pseudopotential mu* using a dielectric matrix approach. An application to Al is made and mu* is estimated to be 0.091. A comparison of the crystal potential, local field, and exchange-correlation effects on the dielectric screening demonstrates that the exchange-correlation effect contributes the largest reduction in mu* compared to that obtained for a free electron gas
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