OPTIMIZATION OF PARAMETERS FOR SEMIEMPIRICAL METHODS .3. EXTENSION OF PM3 TO BE, MG, ZN, GA, GE, AS, SE, CD, IN, SN, SB, TE, HG, TL, PB, AND BI

Using a recently developed procedure for optimizing parameters for semiempirical methods, 1 PM3 has been extended to a total of 28 elements. Average DELTA-H(f) errors for the newly parameterized elements are Be: 8.6, Mg: 8.4, Zn: 5.8, Ga: 14.9, Ge: 11.4, As: 8.5, Se: 11.1, Cd: 2.6, In: 11.3, Sn: 9.0, Sb: 13.7, Te: 11.3, Hg: 6.8, Tl: 6.5, Pb: 7.4, and Bi: 10.9 kcal/mol. For some elements the paucity of data has resulted in a method, which, while highly accurate, is likely to be only poorly predictive.