## Materials Research

### FP-MST

FP-MST is an ab initio electronic structure calculation package for solid state materials. It is based on full-potential (FP) multiple scattering theory (MST), also known as Korringa-Kohn-Rostoker (KKR) method, and solves the Green function for the Kohn-Sham’s equation in Density Functional Theory (DFT).

FP-MST was developed by PSC staff and will be made available for download.

#### Package Description

FP-MST implements KKR method for solving the one-electron Schrödinger equation. Unlike many other ab initio packages, it solves for both core and valence states (also known as “all-electron” method), and it does not use pseudo-potential and plane-wave basis.

FP-MST also implements Locally Self-consistent Multiple Scattering (LSMS) method, a linear scaling, real space MST approach to the solution of the Kohn-Sham’s equation. It is capable of performing the electronic structure calculation for systems that may require tens of thousands of atoms in the unit cell.

FP-MST goes beyond the muffin-tin approximation employed in conventional KKR method, and is capable of performing full-potential electronic structure calculations without requiring the potential and charge density to be spherically symmetrical.

FP-MST takes advantage of computational independence between the processes for each atom, energy mesh point along an energy contour, spin index, k-space mesh point, and angular momentum quantum number, and employs MPI and MPI-group for multi-level parallelization over the processes. FP-MST also takes advantage of GPGPU devices and is able to offload compute intensive calculations to the accelerators if they are available.

FP-MST is designed to perform the following electronic structure calculations:

- Conventional k-space approach to the electronic structure calculation for a crystal with periodic boundary conditions
- Real space approach to the electronic structure calculation for a complex structure
- Spin-polarized calculation for ferromagnetic or anti-ferromagnetic materials
- Spin-canted calculation for materials with non-collinear magnetic structure
- Scalar-relativistic (or semi-relativistic) electronic structure calculation
- Conventional KKR-CPA method with muffin-tin approximation for random alloys
- Full-potential KKR-CPA method for random alloys

#### Starting Potential

Various starting potentials for each element are provided for performing SCF electronic structure calculations. The potential is generated either from a single site calculation or from a SCF electronic structure calculation for a crystal. The muffin-tin potentials are in traditional KKR format.

#### Other KKR-related Projects