Calculations of heats of formation for nitro compounds by semi-empirical mo methods and molecular mechanics

Abstract Heats of formation (δ Hf □) for nitro compounds have been calculated with the semi-empirical molecular orbital theory and the molecular mechanics. Semi-empirical MO method PM3 and molecular mechanics MM2 can estimate δ Hf □ accurately enough for practical use. However, accurate δ Hf □ can't be calculated by MM2 for tetranitromethane which has spatially very crowded structure.