Diamond and beta-tin structures of Si studied with quantum Monte Carlo calculations.
PHYS REV B
, Article 214102. 10.1103/PhysRevB.70.214102.
We have used diffusion quantum Monte Carlo (DMC) calculations to study the pressure-induced phase transition from the diamond to beta-tin structure in silicon. The calculations employ the pseudopotential technique and systematically improvable B-spline basis sets. We show that in order to achieve a precision of 1 GPa in the transition pressure the noncanceling errors in the energies of the two structures must be reduced to 30 meV/atom. Extensive tests on system size errors, nonlocal pseudopotential errors, basis-set incompleteness errors, and other sources of error, performed on periodically repeated systems of up to 432 atoms, show that all these errors together can be reduced to well below 30 meV/atom. The calculated DMC transition pressure is about 3-4 GPa higher than the accepted experimental range of values, and we argue that the discrepancy may be due to the fixed-node error inherent in DMC techniques.
|Title:||Diamond and beta-tin structures of Si studied with quantum Monte Carlo calculations|
|Keywords:||HIGH-PRESSURE PHASES, AB-INITIO, METALLIC MODIFICATIONS, CRYSTAL STRUCTURES, SILICON, GE, TRANSITION, STABILITY, SIMULATIONS, POTENTIALS|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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