Optimization of the spin-component-scaled factor for electron propagator method

[Display omitted] •A new method based on SCS technique for EP2 is proposed.•Second-order self-energy is separated into its spin components.•Opposite spin contributions are overestimated in hydrogen molecule.•Ionization energies are improved with balanced descriptions of self-energy. A cost-free modi...

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Bibliographic Details
Published in:Chemical physics letters 2017-06, Vol.678, p.159-166
Main Authors: Lim, Fang-Han, Nishida, Manami, Hori, Yuta, Ida, Tomonori, Mizuno, Motohiro
Format: Article
Language:English
Subjects:
Electron propagator theory
ex-SCS-EP2
Ionization potential
One-electron Green’s function
Second order self-energy correction
Spin-Component-Scaled
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Summary:[Display omitted] •A new method based on SCS technique for EP2 is proposed.•Second-order self-energy is separated into its spin components.•Opposite spin contributions are overestimated in hydrogen molecule.•Ionization energies are improved with balanced descriptions of self-energy. A cost-free modification of second-order electron propagator theory (ex-SCS-EP2) to improve the description of ionization energies based on spin-component-scaled approximation is proposed. The relaxation part (PRX) and correlation part (PRM) in second-order self-energy are partitioned into parallel- and anti-parallel-spin component then scaled separately. The scaling factors are optimized with 23 valence orbital energies and results shown that ex-SCS-EP2 performs significantly better than regular EP2, SCS-EP2 and OVGF with 0.22eV of mean absolute error (MAE) and 0.11eV of mean absolute deviation (MAD). The effects of SCS parameters on self-energy are also examined to ensure better description in total correlation energy.
ISSN:0009-2614
1873-4448
DOI:10.1016/j.cplett.2017.04.044