Journal ArticleDOI
An Evaluation of Harmonic Vibrational Frequency Scale Factors
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TLDR
A near-linear relationship between the magnitude of the scale factor and the proportion of exact exchange is revealed and hybrid DFT calculations using a modified B3-LYP functional are probed.Abstract:
Scale factors for obtaining fundamental vibrational frequencies, low-frequency vibrational frequencies, zeropoint vibrational energies (ZPVEs), and thermal contributions to enthalpy and entropy have been derived through a least-squares approach from harmonic frequencies determined at more than 100 levels of theory. Wave function procedures (HF, MP2, QCISD, QCISD(T), CCSD, and CCSD(T)) and a large and representative range of density functional theory (DFT) approaches (B3-LYP, BMK, EDF2, M05-2X, MPWB1K, O3-LYP, PBE, TPSS, etc.) have been examined in conjunction with basis sets such as 6-31G(d), 6-31+G(d,p), 6-31G(2df,p), 6-311+G(d,p), and 6-311+G(2df,p). The vibrational frequency scale factors were determined by a comparison of theoretical harmonic frequencies with the corresponding experimental fundamentals utilizing a standard set of 1066 individual vibrations. ZPVE scale factors were generally obtained from a comparison of the computed ZPVEs with experimental ZPVEs for a smaller standard set of 39 molecules, though the effect of expansion to a 48 molecule data set was also examined. In addition to evaluating the scale factors for a wide range of levels of theory, we have also probed the effect on scale factors of varying the percentage of incorporated exact exchange in hybrid DFT calculations using a modified B3-LYP functional. This has revealed a near-linear relationship between the magnitude of the scale factor and the proportion of exact exchange. Finally, we have investigated the effect of basis set size on HF, MP2, B3-LYP, and BMK scale factors by deriving values with basis sets ranging from 6-31G(d) up to 6-311++G(3df,3pd) as well as with basis sets in the cc-pVnZ and aug-cc-pVnZ series and with the TZV2P basis.read more
Citations
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Covalently bonded single-molecule junctions with stable and reversible photoswitched conductivity.
Chuancheng Jia,Agostino Migliore,Na Xin,Shaoyun Huang,Jinying Wang,Qi Yang,Shuopei Wang,Hongliang Chen,Duoming Wang,Boyong Feng,Zhirong Liu,Guangyu Zhang,Da Hui Qu,He Tian,Mark A. Ratner,Hongqi Xu,Abraham Nitzan,Abraham Nitzan,Xuefeng Guo +18 more
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Spectroscopic investigations and quantum chemical computational study of (E)-4-methoxy-2-[(p-tolylimino)methyl]phenol.
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Frequency and zero-point vibrational energy scale factors for double-hybrid density functionals (and other selected methods): can anharmonic force fields be avoided?
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Advances in theory and their application within the field of zeolite chemistry.
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References
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Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
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Journal ArticleDOI
Self-Consistent Equations Including Exchange and Correlation Effects
Walter Kohn,L. J. Sham +1 more
TL;DR: In this paper, the Hartree and Hartree-Fock equations are applied to a uniform electron gas, where the exchange and correlation portions of the chemical potential of the gas are used as additional effective potentials.
Journal ArticleDOI
Inhomogeneous Electron Gas
P. C. Hohenberg,Walter Kohn +1 more
TL;DR: In this article, the ground state of an interacting electron gas in an external potential was investigated and it was proved that there exists a universal functional of the density, called F[n(mathrm{r})], independent of the potential of the electron gas.