Notes for PHY 598 Sect B1 (Venables)

Notes by John A. Venables. This table is in the course of construction. Latest version 7 January 97.

Table B1. Energies of bulk and dimer properties for Si and Ge

Material	spacing (nm)	Energy (eV)	LO freq (THz)
1. Bulk Si calc	 0.545 (lattice 		15.2
            expt 0.5430 constant) 4.63 ± 0.04	15.5
            error <1%		 		<3%
2.     Si2  calc 0.226 (dimer			14.6
            expt 0.225 separation)3.21 ± 0.13	15.4
3. Bulk Ge calc			
            expt 0.5658		  3.83 ± 0.02	
            error			
4.  Ge2 calc  			
            expt		  2.63 ± 0.09	

The argument is that if one gets both bulk Si (Ge) and the dimer Si2 (Ge2) correct, then surfaces, which are in between, must be more or less right. These particular calculations (Northrup, ref to find) gave the surface energy of 1.46 eV/atom for un-reconstructed Si(111) 1x1, and *** for Ge(111) 1x1.