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Problematics for a general interface between electronic structure codes and multiple scattering codes. Keisuke Hatada Dipartimento di Fisica, Universit à Camerino. Electronic structure codes. Widely used methods and codes KKR(SPR-KKR) FLAPW (WIEN2k) Pseudo potential (VASP, Abinit)
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Problematics for a general interface between electronic structure codes and multiple scattering codes Keisuke Hatada Dipartimento di Fisica, UniversitàCamerino
Electronic structure codes Widely used methods and codes • KKR(SPR-KKR) • FLAPW (WIEN2k) • Pseudo potential (VASP, Abinit) • Quantum Chemistry (Gaussian, ADF) • ….
Two main issues for application of these methods, • Construction of WF or charge density and potential • Creation of core hole (Exicted state)
WF/charge density • Which kind of basis sets? atomic orbital, plane waves, numerical, some functions (Wanier,wavelet,etc.) In principle, we can construct WF/charge density from coefficients and basis functions
Problem is Pseudo potential method. In interstitial region, real WF and potential. In atomic region pseudo WF and potential.
Treatment for pseudo stuff • Find a real WF in radial mesh with multipoles VASP (Kruger, Natoli, Hatada) interpolate in radial mesh for all multipoles, for interstitial region just 3d interpolation in Cartesian grid (Abinit; Sipr,Vackar )
For the pseudo potential • It is not standard to have real potential in atomic region with radial mesh. Also, Coulomb and XC part must be separated. => XC potential for electronic structure code is only for ground state, energy constant like Xα potential. We need to use energy dependent complex optical potential.
Poisson equation solver • For VASP, Natoli and Kruger made a code for solving Poisson equation inside atomic region which have the boundary condition of each surface of sphere mach to the solution of interstitial region. => integrated into FPMS
With core hole • Pseudo potential, what can we do in reality? It seems rather abnormal way of usage code. Does someone know it? • For Quantum chemistry codes, people make sometimes half core hole. How do we do?