The harmonic force field and the vibrational spectrum of nitramide were calculated by using the ab initio gradient program TEXAS at the Hartree-Fock level with a 4-21G basis set. The directly computed theoretical harm...The harmonic force field and the vibrational spectrum of nitramide were calculated by using the ab initio gradient program TEXAS at the Hartree-Fock level with a 4-21G basis set. The directly computed theoretical harmonic force field was scaled by using empirical scale factors which are transferred from other molecules and provided an a priori prediction of fundamental frequencies and intensities. The average deviations between predicted vibrational frequencies of nitramide and experimental IR spectrum in an argon matrix are 63 cm-1 for symmetric vibrations and 41 cm-1 for antisymmetric modes. A new set of scale factors was optimized in this paper. These scale factors reduced the average deviations to 2. 3 cm-1 for symmetric modes and 0. 8 cm-1 for antisymmetric ones. The vibrational spectra of three isotopic derivatives of nitramide were predicted by using the force field resulted from the optimized set of scale factors, which are in good agreement with their experimental data in an argon matrix.展开更多
The complete harmonic vibrational force field of dimethylnitramine has been calculated at the Hartree-Fock level using 4-21G basis set.The harmonic force field was then scaled with scale factors previously derived fro...The complete harmonic vibrational force field of dimethylnitramine has been calculated at the Hartree-Fock level using 4-21G basis set.The harmonic force field was then scaled with scale factors previously derived from N-methylnitramine,and the vibrational spectrum of dimethylnitramine was 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 the scale factors were reoptimized by fitting of the computed force field to experimental data.The new set of scale factors reduced the mean deviation to 4.5 cm^(-1),and was used to predict the vibrational spectrum 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.展开更多
基金Supported by the National Natural Science Foundation of China
文摘The harmonic force field and the vibrational spectrum of nitramide were calculated by using the ab initio gradient program TEXAS at the Hartree-Fock level with a 4-21G basis set. The directly computed theoretical harmonic force field was scaled by using empirical scale factors which are transferred from other molecules and provided an a priori prediction of fundamental frequencies and intensities. The average deviations between predicted vibrational frequencies of nitramide and experimental IR spectrum in an argon matrix are 63 cm-1 for symmetric vibrations and 41 cm-1 for antisymmetric modes. A new set of scale factors was optimized in this paper. These scale factors reduced the average deviations to 2. 3 cm-1 for symmetric modes and 0. 8 cm-1 for antisymmetric ones. The vibrational spectra of three isotopic derivatives of nitramide were predicted by using the force field resulted from the optimized set of scale factors, which are in good agreement with their experimental data in an argon matrix.
基金Project supported by the National Natural Science Foundation of China.
文摘The complete harmonic vibrational force field of dimethylnitramine has been calculated at the Hartree-Fock level using 4-21G basis set.The harmonic force field was then scaled with scale factors previously derived from N-methylnitramine,and the vibrational spectrum of dimethylnitramine was 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 the scale factors were reoptimized by fitting of the computed force field to experimental data.The new set of scale factors reduced the mean deviation to 4.5 cm^(-1),and was used to predict the vibrational spectrum 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.
