A molecular dynamics study of the relaxation of an excited molecule in crystalline nitromethane

Classical molecular dynamics simulations were used to study the relaxation of an excited nitromethane molecule in perfect crystalline nitromethane at 250 K and 1 atm pressure. The molecule was instantaneously excited by statistically distributing energy E∗ between 25.0 kcal/mol and 125.0 kcal/mol among the 21 degrees of freedom of the molecule. The relaxation occurs exponentially with time constants between 11.58 ps and 13.57 ps. Energy transfer from the excited molecule to surrounding quasi-spherical shells of molecules occurs concurrently to both the nearest and next-nearest neighbor shells, but with more energy per molecule transferred more rapidly to the first shell.