Anharmonicity vibrational frequencies

Hobza, P., Bludsky, O. Suhai, S., 1999, Reliable Theoretical Treatment of Molecular Clusters Counterpoise-Corrected Potential Energy Surface and Anharmonic Vibrational Frequencies of the Water Dimer , Phys. Chem. Chem. Phys., 1, 3073. 

Harmonic vibrational frequency (cm-1) calc.crf Ohserved (anharmonic) vibrational frequency (cm" ) in 1R absorption Harmonic vibrational frequency (cm-1) calc.c Observed (anharmonic) vibrational frequency (cm-1) in IR absorption ... 

TABLE 19.1 Gibbs free energy (at 298 K and 1 atm reference pressure) for the addition of water molecules to sulfuric acid, from various calculations and experiments. For the quantum chemical results, the use of harmonic or anharmonic vibrational frequencies has been indicated... 

Jacobsen, R. L. Johnson, R. D. Irikura, K. K. Kacker, R. N. Anharmonic vibrational frequency calculations are not worthwhile for small basis sets, 7. Chem. Theor. Comput. 2013, 9, 951-954. 

For numerous ion... polar molecule hydrogen bonded ccanplexes harmonic and anharmonic vibrational frequencies were calculated and compared with observed ones for the respective references see Ref. . A detailed description of calculating vibrational spectra and infrared absorption intensities is given in a study on the (CH3SH)2 dimer " . 

Table 2.4. Experimental Harmonic and Anharmonic Vibrational Frequencies for...

Figure 12. Plots of the binding energy Eh, anharmonic vibrational frequency vm.a, static dipole moment /t, dynamic dipole moment /, Hitshfeld charge Oh, and equilibrium bond distance r, as a function of the external field for hollow-site adsorbed Na (diamonds), O (circles), C (squares), and I (triangles) on 13-atom Pt clusters. Reprinted with permission fi-om S. A. Wasileski e al., J. Chem. Phys., IIS, (2001) 8193. Copyright 2001, American Institute of Physics...

Vibrational Frequencies. As noted in Section 15.13, theoretically calculated vibrational frequencies are often multiplied by a scale factor to improve agreement with experiment. For a set of 122 molecules and 1066 vibrational frequencies, scaled theoretical harmonic vibrational frequencies showed the following rms deviations from experimental fundamental (anharmonic) vibrational frequencies also given are the optimum scale factors and the percentages of scaled frequencies with less than 6% error and more than 20% error [A. P. Scott and L. Radom,/ Phys. Chem., 100,16502 (19%)] ... 

Biczysko M, Panek P, Scalmani G, Bloino J, Barone V (2010) Harmonic and anharmonic vibrational frequency calculations with the double-hybrid b2plyp method analytic second derivatives and benchmark studies. J Chem Theory Comput 6 2115-2125. doi 10.1021/ctl00212p... 

Harmonic vibrational frequencies [3, 8-10] Infrared harmonic absorption intensities [11] Anharmonic vibrational frequencies [12] Raman intensities (harmonic approximation) [13, 14]... 

Table 7.2 MUEs of Anharmonic Vibrational Frequencies (cm Computed by Several DFT/N07D and Hybrid CCSD(T) + DFT Models for HjCN, FCS, and NH2 Radicals as Compared to Experimental Data"...

Table 7.3 Averaged MUEs, MIN MAX Deviations of Anharmonic Vibrational Frequencies (cm ) Computed by Several DFT Models for Pyridine, Furan, Pyrrole, and Thiophene, and Compared to Experimental Reference Data"...

Calculation of anharmonic vibrational frequencies for large systems and molecular clusters is an exceptionally demanding task and no routine code exists. The multidimensional vibrational Schrodinger equation was recently solved for aniline (model molecule to study amino group pyramidalization) and the adenine... thymine Watson-Crick (AT WC) base pair further, the one-dimensional problem was solved for the buckle vibrations of the GC WC and GGl base pairs. Inversion splitting for aniline and aniline-ND2 was evaluated by solving a two-dimensional vibrational Schrodinger equation... 

Table 10.9 Anharmonic vibrational frequencies of chlorophyll-a cation in tetrahydrofuran solution computed considering each mode one-by-one (1M) or taking into account all couplings between C=0 vibrations (3M).

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