Studies on nitramide and its methyl derivatives with ab initio calculations——Ⅳ.The harmonic force fi

• 出 处: Chinese Journal of Chemistry
• 发表日期: 1993年03期
• 关键词: deviation isotopic vibrational harmonic Hartree fitting sealed scaled comparable

The complete harmonic vibrational force field of dimethylnitramine has been calculatedat the Hartree-Fock level using 4-21G basis set.The harmonic force field was then scaled with scalefactors previously derived from N-methylnitramine,and the vibrational spectrum of dimethylnitraminewas computed.This apriori prediction,made with no reference to observations on dimethylnitramine,agrees with the experimental IR spectrum in gas phase with a mean deviation of 8.4 cm~(-1).Some of thescale factors were reoptimized by fitting of the computed force field to experimental data.The newset of scale factors reduced the mean deviation to 4.5 cm~(-1),and was used to predict the vibrationalspectrum of deuterated form of dimethylnitramine(-6D).Dipole moment derivatives were also cal-culated and used to predict infrared intensities which are comparable with experimental values.