Approaching bulk limit for three-dimensional solids via the cyclic clusterapproximation: Semiempirical INDO study

The cyclic cluster method has been examined for a number of solids using a recently developed computer code, SOLID98. Calculations are based on the qu asirelativistic (QR) INDO/1 (intermediate neglect of differential overlap) method that is simple enough to allow for a saturation of the (cyclic) clus ters. Convergence toward the bulk limit (INDO/1) charge density with respec t to the size of the model cyclic cluster is shown for diamond, silicon, ge rmanium, boron nitride, gallium phosphide, gallium arsenide, and gallium an timonide. Results show that, as soon as the initial cluster size reaches 5 to 6 nm, one can safely use the obtained density matrix as a good approxima tion to the bulk limit. (C) 1999 John Wiley & Sons, Inc.