Showing papers by "David Vanderbilt published in 1990"
TL;DR: Novel features are that the pseudopotential itself becomes charge-state dependent, the usual norm-conservation constraint does not apply, and a generalized eigenproblem is introduced.
Abstract: A new approach to the construction of first-principles pseudopotentials is described. The method allows transferability to be improved systematically while holding the cutoff radius fixed, even for large cutoff radii. Novel features are that the pseudopotential itself becomes charge-state dependent, the usual norm-conservation constraint does not apply, and a generalized eigenproblem is introduced. The potentials have a separable form well suited for plane-wave solid-state calculations, and show promise for application to first-row and transition-metal systems.
18,782 citations
TL;DR: It is predicted that the single-layer stepped surface is at equilibrium for small misorientation angles and this structure is stabilized by strain relaxation and by the thermal roughening of the steps.
Abstract: The phase diagram of vicinal Si(100) as a function of misorientation angle and temperature is calculated. Contrary to previous suggestions that only double-layer steps should appear on the equilibrium surface, it is predicted that the single-layer stepped surface is at equilibrium for small misorientation angles. This structure is stabilized by strain relaxation and by the thermal roughening of the steps. For annealed surfaces the critical angle at which the transition between the single- and double-layer stepped surface occurs is calculated to be ${\mathrm{\ensuremath{\theta}}}_{\mathit{c}}$\ensuremath{\approxeq}2\ifmmode^\circ\else\textdegree\fi{}.
215 citations
TL;DR: In this paper, the elastic energies associated with the evolution of a uniform strained overlayer as it segregates into coherent islands were investigated in the context of a two-dimensional model and the conditions under which coherent islands may be energetically favored over both uniform epitaxial films and dislocated islands.
Abstract: Motivated by recent observations of coherent Ge island formation during growth of Ge on Si (100), we have carried out a theoretical study of the elastic energies associated with the evolution of a uniform strained overlayer as it segregates into coherent islands. In the context of a two-dimensional model, we have explored the conditions under which coherent islands may be energetically favored over both uniform epitaxial films and dislocated islands. We find that if the interface energy (for dislocated islands) is more than about 15% of the surface energy, then there is a range of island sizes for which the coherent island structure is preferred.
37 citations
TL;DR: A factor-of-3 error was recently found in the computer code used to generate the cubic and quartic contributions to the internal energies in the high-temperature limit, which invalidates the estimate for the Ill term and causes the sign of the Ill to be erroneously negative.
Abstract: A factor-of-3 error was recently found in the computer code used to generate the cubic and quartic contributions to the internal energies in the high-temperature limit. This error causes the values we reported for u3 and u4 in the hightemperature limit to be exactly —, ' of their true values. Thus, instead of 7.198 and 3.551, u3 and u4 should be 21.594 and 10.653, respectively This error also invalidates the estimate for the Ill term in Eq. (6b). In addition, a typographical error caused the sign of the Ill to be erroneously negative. Equation (6b) should therefore read
7 citations