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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Harmonic Vibrational Frequencies:Scaling Factors for HF,B3LYP,and MP2 Methods in Combination with Correlation Consistent Basis Sets
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Harmonic Vibrational Frequencies:Scaling Factors for HF,B3LYP,and MP2 Methods in Combination with Correlation Consistent Basis Sets

机译：谐波振动频率：HF，B3LYP和MP2方法与相关一致基集组合的比例因子

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摘要

A least-squares approach has been used to determine multiplicative scaling factors for harmonic vibrational frequencies to facilitate comparison with experimentally observed frequencies.The harmonic frequencies were calculated using several of the most popular quantum chemical methods (HF,MP2,and B3LYP) and the correlation consistent family of basis sets (cc-pVxZ and aug-cc-pVxZ,where x=D(2),T(3),or Q(4)).Calculations were performed on 41 organic molecules for which fundamental frequencies are well established.When the derived scaling factors are applied,the percentage of calculated frequencies that deviate less than 3% from the experimental frequencies is 93-97% for B3LYP and 88-92% for MP2 when quadruple- zeta level basis sets are used.Similarly,scaling factors were determined for computing the vibrational components of the thermal contributions to enthalpy and entropy.An additional set of molecules was used in calculating scaling factors for the zero-point vibrational energy.
机译：已使用最小二乘法确定谐波振动频率的乘法比例因子，以便于与实验观察到的频率进行比较。谐波频率是使用几种最流行的量子化学方法（HF，MP2和B3LYP）及其相关性来计算的一致的基集族（cc-pVxZ和aug-cc-pVxZ，其中x = D（2），T（3）或Q（4））。对41个有机分子进行了计算，这些有机分子的基本频率已经很好地建立了当使用推导的比例因子时，使用四重zeta水平基集时，与实验频率偏差小于3％的计算频率百分比为B3LYP为93-97％，MP2为88-92％。确定比例因子以计算热对焓和熵的贡献的振动分量。使用另一组分子来计算零点振动能量的比例因子。

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