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采用五个密度泛函LSDA,B3LPY,B3PW91,MPW1PW91和PBE1PBE,选择不同基组计算了气相和乙醇为溶剂下的丹皮酚及其两个丹皮酚西佛碱的激发态。LSDA不能给出合理的结果,MPW1PW91和PBE1PBE的结果和实验值接近,而B3LYP能给出准确的垂直激发能。基组中加入弥散函数有利于激发能计算精度的提高。溶剂效应对激发态计算的准确度有明显影响,极化连续模型(PCM)能较好地模拟溶剂的影响,垂直激发能计算结果明显好于气相。
Five different density functional groups (LSDA, B3LPY, B3PW91, MPW1PW91 and PBE1PBE) were used to calculate the excited states of paeonol and two paeonol Schiff bases in gas and ethanol as solvent. LSDA can not give reasonable results, the results of MPW1PW91 and PBE1PBE are close to the experimental values, and B3LYP can give accurate vertical excitation energy. Addition of dispersion function in the basis set is beneficial to improve the calculation accuracy of excitation energy. Solvent effect has obvious influence on the accuracy of excited state calculation. Polarization continuum model (PCM) can better simulate the effect of solvent, and the calculated result of vertical excitation energy is obviously better than that of gas phase.