Problematics for a general interface between electronic structure codes and multiple scatter

ing codes

Keisuke Hatada

Dipartimento di Fisica, Università Camerino

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?