DERIVATION OF MM2 FORCE-FIELD PARAMETERS FOR POLYCHLOROPHOSPHAZENES (NPCL2)N FROM AB-INITIO DATA

Derivation of force-field parameters for chlorophosphazenes was perfor med through the technique of energy derivatives starting from ab initi o calculated data. The SCF method at the 4-31G level provided the ene rgy surface for the model compound OP2NCl5. The ab initio search of mi nima (STO-3G, 4-31G*, 6-31G* basis sets) was also made for the oligom er OP3N2Cl7. The results were compared with those obtained by molecula r mechanics including the calculated parameter sets for the MM2 atom t ypes: 25 (P), 9 (N), 7 (O), 12 (Cl). The force-field method improved b y the obtained force constants compared quite well with the results pr oduced by the quantum mechanical SCF calculations.