Six low-lying tautomers of 1-methyl-hypoxanthine have been studied at the B3LYP/aug-cc- pVDZ level. Two tautomers NTH and N9H with the comparable energies are far more stable than the others. The vertical ionization e...Six low-lying tautomers of 1-methyl-hypoxanthine have been studied at the B3LYP/aug-cc- pVDZ level. Two tautomers NTH and N9H with the comparable energies are far more stable than the others. The vertical ionization energies of the tautomers calculated with ab initio electron propagator theory in the P3/aug-cc-pVDZ approximation are in agreement with the experimental data from photoelectron spectroscopy. According to the calculated relative energies and the comparison between the simulated and the experimental photoelectron spectra, it demonstrates that there are at least two tautomers of 1-methyl-hypoxanthine in the gas-phase experiments.展开更多
Fourteen conformers of 3-amino-1-propanol as the minima on the potential energy surface are examined at the MP2/6-311＋＋G＊＊ level. Their relative energies calculated at B3LYP, MP3 and MP4 levels of theory indicated...Fourteen conformers of 3-amino-1-propanol as the minima on the potential energy surface are examined at the MP2/6-311＋＋G＊＊ level. Their relative energies calculated at B3LYP, MP3 and MP4 levels of theory indicated that two most stable conformers display the intramolecular OH - N hydrogen bonds. The vertical ionization energies of these conformers calculated with ab initio electron propagator theory in the P3/aug-cc-pVTZ approximation are in agreement with experimental data from photoelectron spectroscopy. Natural bond orbital analyses were used to explain the differences of IEs of the highest occupied molecular ortibal of conformers. Combined with statistical mechanics principles, conformational distributions at various temperatures are obtained and the temperature dependence of photoelectron spectra is interpreted.展开更多
文摘Six low-lying tautomers of 1-methyl-hypoxanthine have been studied at the B3LYP/aug-cc- pVDZ level. Two tautomers NTH and N9H with the comparable energies are far more stable than the others. The vertical ionization energies of the tautomers calculated with ab initio electron propagator theory in the P3/aug-cc-pVDZ approximation are in agreement with the experimental data from photoelectron spectroscopy. According to the calculated relative energies and the comparison between the simulated and the experimental photoelectron spectra, it demonstrates that there are at least two tautomers of 1-methyl-hypoxanthine in the gas-phase experiments.
基金This work was supported by the Province Natural Science Foundation of Henan （No.082300410030）, the Foundation of Henan Educational Committee （No.2011A140015）, and the Doctoral Research Pund of Henan Normal University （No.525449）.
文摘Fourteen conformers of 3-amino-1-propanol as the minima on the potential energy surface are examined at the MP2/6-311＋＋G＊＊ level. Their relative energies calculated at B3LYP, MP3 and MP4 levels of theory indicated that two most stable conformers display the intramolecular OH - N hydrogen bonds. The vertical ionization energies of these conformers calculated with ab initio electron propagator theory in the P3/aug-cc-pVTZ approximation are in agreement with experimental data from photoelectron spectroscopy. Natural bond orbital analyses were used to explain the differences of IEs of the highest occupied molecular ortibal of conformers. Combined with statistical mechanics principles, conformational distributions at various temperatures are obtained and the temperature dependence of photoelectron spectra is interpreted.
