The equilibrium geometries of nitramide, methylnitramide and dimethylnitramide have been optimized by the ab initio gradient program TEXAS using the 4-21 G basis set of Gaussian orbitals. The predicted bond lengths, which were determine according to the optimized bond lengths together with some corresponding empirical corrections, agree with the experimental results for C-N, N-H and C-H. A possible empirical correction for N-N lengths and a simple empirical formula of corrections for N-O lengths with the 4-21G basis set were discussed.

Key words: GRADIENTS, CHEMICAL BONDS, AB INITIO CALCULATION, OPTIMIZATION ALGORITHMS, SELF-CONSISTENT FIELD, CONFIGURATION, FORCE CONSTANT, NITRAMINE, BOND LENGTH, BOND ANGLE