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130th General Meeting of Korean Chemical Society Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory for Accurate X-ray Absorption Spectroscopy

Submission Date :
8 / 2 / 2022 , 11 : 30 : 45
Abstract Number :
Presenting Type:
Poster Presentation
Presenting Area :
Physical Chemistry
Authors :
Woojin Park, Cheol Ho Choi1,*
Chemistry, Kyungpook National University, Korea
1Department of Chemistry, Kyungpook National University, Korea
Assigned Code :
Presenting Time :
It is demonstrated that the challenging core hole-particle (CHP) orbital relaxation for core electron spectra can be readily achieved by the mixed-reference spin-flip (MRSF)-TDDFT. With the additional scalar relativistic effects on K-edge excitation energies of 24 second- and 17 third-row molecules, the particular ΔCHP-MRSF(R) exhibited near perfect predictions with RMSE ~ 0.5 eV, featuring a median value of 0.3 and an interquartile range of 0.4. Overall, the CHP effect is 2 ~ 4 times stronger than relativistic ones, contributing more than 20 eV in the cases of sulfur and chlorine third-row atoms. Such high precision allows to explain the splitting and spectral shapes of O, N and C atom K-edges in the ground state of thymine with atom as well as orbital specific accuracy. The same protocol with a double hole particle relaxation also produced remarkably accurate K-edge spectra of core to valence hole excitation energies from the first (nO8π*) and second (ππ*) excited states of thymine, confirming the assignment of 1s → n excitation for the experimentally observed 526.4 eV peak.Regarding both accuracy and practicality, therefore, MRSF-TDDFT provides a promising protocol for core electron spectra both of ground and excited electronic states alike.