TOTAL-ENERGY CALCULATIONS OF RANDOM ALLOYS - SUPERCELL, CONNOLLY-WILLIAMS, AND CPA METHODS

We compare the results of total energy calculations obtained by three most popular methods, the supercell method, the Connolly-Williams (CW) method, and the coherent potential approximation (CPA). As a referenc e we use the result for a supercell of 256 atoms obtained by the order -N locally self-consistent Green's function (LSGF) method. We show tha t for the particular case of a fee Ag-Au alloy there is satisfactory a greement between the different techniques. Moreover, we demonstrate th at in the framework of the CPA and the screened impurity model (SIM) o ne may obtain a reliable description of the total energy of a random a lloy. Copyright (C) 1998 Elsevier Science B.V.