화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.115, No.30, 8375-8379, 2011
Dissociation of H2NCH Dication in a Strong Laser Field
Ab initio classical molecular dynamics calculations have been used to simulate the dissociation of H2NCH2+ in a strong laser field. The frequencies of the continuous oscillating electric field were chosen to be omega = 0.02, 0.06, and 0.18 au (2280, 760, and 253 nm, respectively). The field had a maximum strength of 0.03 au (3.2 x 10(13) W cm(-2)) and was aligned with the CN bond. Trajectories were started with 100 kcal/mol of vibrational energy above zero point and were integrated for up to 600 fs at the B3LYP/6-311G(d,p) level of theory. A total of 200 trajectories were calculated for each of the three different frequencies and without a field. Two dissociation channels are observed: HNCH+ + H+ and H2NC+ + H+. About one-half to two-thirds of the H+ dissociations occurred directly, while the remaining indirect dissociations occurred at a slower rate with extensive migration of H+ between C and N. The laser field increased the initial dissociation rate by a factor of ca. 1.4 and decreased the half-life by a factor of ca. 0.75. The effects were similar at each of the three frequencies. The HNCH+ to H2NC+ branching ratio decreased from 10.6:1 in the absence of the field to an average of 8.4:1 in the laser field. The changes in the rates and branching ratios can be attributed to the laser field lowering the reaction barriers as a result of a difference in polarizability of the reactant and transition states.