Ab initio SCF and Moller-Plesset correlation correction methods incombination with counterpoise procedure for BSSE correction have been applied to the theroeticalstudying of dimethylnitroamine and its dimers and trime...Ab initio SCF and Moller-Plesset correlation correction methods incombination with counterpoise procedure for BSSE correction have been applied to the theroeticalstudying of dimethylnitroamine and its dimers and trimers. Three optimized stable dimers and twotrimers have been obtained. The corrected binding energies of the most stable dimer and trimer werepredicted to be - 24.68 kJ/mol and - 47.27 kJ/mol, respectively at the MP2/6-31G ~*//HF/6-31G~*level. The proportion of correlated interaction energies to their total interaction energies for allclusters was at least 29.3 percent, and the BSSE of ΔE(MP2) was at least 10.0 kJ/mol. Dispersionand/ or electrostatic force were dominant in all clusters. There exist cooperative effects in boththe chain and the cyclic trimers. The vibrational frequencies associated with N―O stretches or wagsexhibit slight red shifts, but the modes associated with the motion of hydrogen atoms of the methylgroup show somewhat blue shifts with respect to those of monomer. Thermodynamic properties ofdimethylnitroamine and its clusters at different temperatures have been calculated on the basis ofvibrational analyses. The changes of the Gibbs free energies for the aggregation from monomer to themost stable dimer and trimer were predicted to be 14.37 kJ/mol and 30.40 kJ/mol, respectively, at 1atm and 298.15 K.展开更多
文摘Ab initio SCF and Moller-Plesset correlation correction methods incombination with counterpoise procedure for BSSE correction have been applied to the theroeticalstudying of dimethylnitroamine and its dimers and trimers. Three optimized stable dimers and twotrimers have been obtained. The corrected binding energies of the most stable dimer and trimer werepredicted to be - 24.68 kJ/mol and - 47.27 kJ/mol, respectively at the MP2/6-31G ~*//HF/6-31G~*level. The proportion of correlated interaction energies to their total interaction energies for allclusters was at least 29.3 percent, and the BSSE of ΔE(MP2) was at least 10.0 kJ/mol. Dispersionand/ or electrostatic force were dominant in all clusters. There exist cooperative effects in boththe chain and the cyclic trimers. The vibrational frequencies associated with N―O stretches or wagsexhibit slight red shifts, but the modes associated with the motion of hydrogen atoms of the methylgroup show somewhat blue shifts with respect to those of monomer. Thermodynamic properties ofdimethylnitroamine and its clusters at different temperatures have been calculated on the basis ofvibrational analyses. The changes of the Gibbs free energies for the aggregation from monomer to themost stable dimer and trimer were predicted to be 14.37 kJ/mol and 30.40 kJ/mol, respectively, at 1atm and 298.15 K.
