We propose new approximate global multiplicative scaling factors for the DFT calculation of ground state harmonic vibrational frequencies using functionals from the TPSS, M06, and M11 functional families with standard correlation consistent cc-pVxZ and aug-cc-pVxZ (x = D, T, and Q), 6-311G split valence family, Sadlej and Sapporo polarized triple-ζ basis sets. Results for B3LYP, CAM-B3LYP, B3PW91, PBE, and PBE0 functionals with these basis sets are also reported. A total of 99 harmonic frequencies were calculated for 26 gas-phase organic and nonorganic molecules typically found in detonated solid propellant residue. Our proposed approximate multiplicative scaling factors are determined using a least-squares approach comparing the computed harmonic frequencies to experimental counterparts well established in the scientific literature. A comparison of our work to previously published global scaling factors is made to verify method reliability and the applicability of our molecular test set.

Harmonic Vibrational Frequencies: Approximate Global Scaling Factors for TPSS, M06, and M11 functional families using several common basis sets

Novel oxovanadium and dioxomolybdenum complexes of tridentate ONO-donor Schiff base ligand: Synthesis, characterization, crystal structures, Hirshfeld surface analysis, DFT computational studies and catalytic activity for the selective oxidation of benzylic alcohols

Abstract The performance of ab initio and density functional theory (DFT) methods in calculating the vibrational wavenumbers in the isolated state was analyzed. To correct the calculated values, several scaling procedures were described in detail. The two linear scaling equation (TLSE) procedure leads to the lowest error and it is recommended for scaling. A comprehensive compendium of the main scale factors and scaling equations available to date for a good accurate prediction of the wavenumbers was also shown. Examples of each case were presented, with special attention to the benzene and uracil molecules and to some of their derivatives. Several DFT methods and basis sets were used. After scaling, the X3LYP/DFT method leads to the lowest error in these molecules. The B3LYP method appears closely in accuracy, and it is also recommended to be used. The accuracy of the results in the solid state was shown and several additional corrections are presented.

DFT computations on vibrational spectra: Scaling procedures to improve the wavenumbers

Diverse coordination of isoniazid hydrazone Schiff base ligand towards iron(III): Synthesis, characterization, SC-XRD, HSA, QTAIM, MEP, NCI, NBO and DFT study

Synthesis, spectral characterization, SC-XRD, HSA, DFT and catalytic activity of a dioxidomolybdenum complex with aminosalicyl-hydrazone Schiff base ligand: An experimental and theoretical approach

Abstract Computational chemistry can be applied to vibrational spectroscopy in different ways, such as for a better characterization and assignment of all the bands of the experimental spectra, as a tool in the identification of the tautomers present in the gas phase and in the solid state through their spectra and for the simulation of the solid and liquid phase of a compound and the consequent simulation and interpretation of their spectra. In the present study, as an example of the applicability of computational chemistry, the structure and spectra of cytosine and uracil nucleic acid bases and two cytosine derivatives are shown. The FTIR and Raman spectra were analysed with the support of ab initio (Hartree-Fock (HF), MP2) and density functional theory (DFT) (B3LYP, PBE, B-P, etc.) calculations using several basis sets and several scaling equations. The calculations predict an easier tautomerization of cytosine than uracil molecule, but the tautomerization is hindered in the 5-bromocytosine molecule. Thus, in the solid state, this molecule only exists in the amino-oxo tautomeric form.

Computational chemistry applied to vibrational spectroscopy: A tool for characterization of nucleic acid bases and some of their 5-substituted derivatives

M. Alcolea Palafox

Papers

DFT computations on vibrational spectra: Scaling procedures to improve the wavenumbers

Computational chemistry applied to vibrational spectroscopy: A tool for characterization of nucleic acid bases and some of their 5-substituted derivatives