Table 2. Scale factors for ab initio model vibrational frequencies adapted from (Scott and Radom 1996). Please note that these scale factors are determined by comparing model and measured frequencies on a set gas-phase molecules dominated by molecules containing low atomic-number elements (H-Cl). These scale factors may not be appropriate for dissolved species and molecules containing heavier elements, and it is always a good idea to directly compare calculated and measured frequencies for each molecule studied. The root-mean-squared (rms) deviation of scaled model frequencies relative to measured frequencies is also shown, giving an indication of how reliable each scale factor is. |

The comparison of the vibrational modes energies, determined by i) Raman scattering, ii) fluorescence, iii) ab initio calculation, and iv) absorption, is reported in Table 6-5. We note that, as in the case of T4 [64], the C=C stretching mode of 1460 cm-1 in the ground slate decreases its frequency significantly (1275 cm-1) in the first excited electronic state. [Pg.416]

A. Bleiber and J. Sauer, The vibrational frequency of the donor OH group in the H bonded dimers of water, methanol and silanol. Ab initio calculations including anharmonicities. Chem. Phys. Lett. 238, 243 252 (1995). [Pg.53]

In order to assign more IR signals of 4a, ab initio calculations on Hbdmpza (3b) and 4a were performed. It is well known for the chosen HF/6-31G basis set that calculated harmonical vibrational frequencies are typically overestimated compared to experimental data. These errors arise from the neglecting anharmonicity effects, incomplete incorporation of electron correlation and the use of finite basis sets in the theoretical treatment (89). In order to achieve a correlation with observed spectra a scaling factor (approximately 0.84-0.90) has to be applied (90). The calculations were calibrated on the asymmetric carboxylate Vasym at 1653 cm. We were especially interested in [Pg.115]

Schultz H, Lehmann H, Rein M, Hanack M (1991) Phthalocyaninatometal and Related Complexes with Special Electrical and Optical Properties. 74 41-146 Schutte CJH (1971) The Ab-Initio Calculation of Molecular Vibrational Frequencies and Force Constants. 9 213-263 [Pg.255]

One of the hurdles in this field is the plethora of definitions and abbreviations in the next section I will attempt to tackle this problem. There then follows a review of calculations of non-linear-optical properties on small systems (He, H2, D2), where quantum chemistry has had a considerable success and to the degree that the results can be used to calibrate experimental equipment. The next section deals with the increasing number of papers on ab initio calculations of frequency-dependent first and second hyperpolarizabilities. This is followed by a sketch of the effect that electric fields have on the nuclear, as opposed to the electronic, motions in a molecule and which leads, in turn, to the vibrational hyperpolarizabilities (a detailed review of this subject has already been published [2]). Section 3.3. is a brief look at the dispersion formulas which aid in the comparison of hyperpolarizabilities obtained from different processes. [Pg.4]

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