Vibrational modes electronic values correction

We studied the system of two electronic levels coupled to two mutually interacting vibrational modes. The first mode contributed to the Stokes shift and Flerzberg-Teller correction (inter-state coupling), while the second mode only to the Stokes shift. In this sense the influence of the second mode to the electronic state transition is indirect. We proved that the second mode increases the excited state decay for increasing value of the Stokes shift,... 

Overview Over the last few decades, quanmm chemistry has evolved into a predictive tool for the calculation of energy differences. Of equal importance as a driving force for chemical reactions is the entropy that has received less attention from the computational community. The predictive value of computed rate constants depends not only on the accuracy of the electronic structure calculations but also on the correct description of the molecular entropy, including anharmonic effects in the vibrational modes, which is subject of Section 7.3.1.3. 

This value of electron affinity, calculated from the bottom of the potential energy well, must be corrected for the zero-point energy (ZPE) effects. It may be expected that the normal modes of the anion will be softer than in SF6 and the ZPE correction will increase the computed value of electron affinity. In order to establish the magnitude of ZPE and determine the character of the stationary point for the anion, harmonic vibrational analysis was performed. Due to limited computer resources, only the DF1 calculations were done using the extended, (3dl/, 3dlf) polarized basis set. Zero-point energies were found to be 0.51 eV and 0.32 eV for SF6 and SFg, respectively the ZPE correction to the computed value of electron affinity is thus about 0.2 eV, and the ZPE-corrected value of electron affinity is 1.6 eV. 

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