Phase transformation in Si from semiconducting diamond to metallic -Sn phase in QMC and DFT under hydrostatic and anisotropic stress

R. G. Hennig,1,2,* A. Wadehra,2 K. P. Driver,2 W. D. Parker,2 C. J. Umrigar,3 and J. W. Wilkins2 1Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501, USA 2Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA 3Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA Received 6 February 2010; revised manuscript received 27 May 2010; published 2 July 2010