Prediction of vibrational spectra by the CNDO/2 force method

Surface-Enhanced Raman Spectra of Phthalimide. Interpretation of the SERS Spectra of the Surface Complex Formed on Silver Islands and Colloids

“…Computed harmonic frequencies typically overestimate vibrational fundamentals due to basis set truncation and neglect of electron correlation and mechanical anharmonicity . To compensate for these shortcomings, various scaling strategies exist for bringing the computed frequencies into greater coincidence with observed wavenumbers. − In this report we have employed the simplest scheme, that of homogeneous scaling. The Hartree−Fock and S-VWN frequencies were scaled using the empirical scaling factors, 0.8953 and 0.9833 respectively, as suggested by Scott and Radom, and Wong. , …”

DFT calculation of the chromyl nitrate, CrO2(NO3)2

“…The harmonic force field in Cartesian coordinates for chromyl nitrate which resulted from the calculations were transformed to "natural" internal coordinates [28] by the MOLVIB program [29,30]. The natural coordinates for monodentate and bidentate chromyl nitrate are shown in Tables 1 and 2, respectively, and have been defined as proposed by Fogarasi and Pulay [31]. Also, the analysis as bidentate ligand was performed with the three basis sets considering the nitrate groups as two rings of four members where the deformations and torsion coordinates of these groups have been defined as proposed by Fogarasi and Pulay [31] and are observed in Table 3.…”

Comparison study of the prediction of Raman intensities using electronic structure methods

“…Various scaling strategies exist to help bring computed frequencies into greater agreement with observed wavenumbers. [52][53][54][55] Usually the simplest scaling strategy is adopted, that of homogeneous scaling. Previous work by Scott and Radom 7 , and Wong 8 have shown that DFT consistently predicts vibrational frequencies in better agreement with observed fundamentals than conventional ab initio methods, with hybrid DFT having low mean absolute errors and scaling factors close to unity.…”