OPENMX Plugin

Features & Capabilities

OpenMX (Open source package for Material eXplorer) is a software package for nano-scale material simulations based on density functional theories (DFT), norm-conserving pseudopotentials, and pseudo-atomic localized basis functions. The methods and algorithms used in OpenMX and their implementation are carefully designed for the realization of large-scale ab initio electronic structure calculations on parallel computers based on the MPI or MPI/OpenMP hybrid parallelism.

Summary

 The efficient implementation of DFT enables us to investigate electronic, magnetic, and geometrical structures of a wide variety of materials such as bulk materials, surfaces, interfaces, liquids, and low-dimensional materials. Systems consisting of 1000 atoms can be treated using the conventional diagonalization method if several hundreds cores on a parallel computer are used. Even ab initio electronic structure calculations for systems consisting of more than 10000 atoms are possible with the O(N) methods implemented in OpenMX if several thousands CPU cores on a parallel computer are available. Since optimized pseudopotentials and basis functions, which are well tested, are provided for many elements, users may be able to quickly start own calculations without preparing those data by themselves. Considerable functionalities have been implemented for calculations of physical properties such as magnetic, dielectric, and electric transport properties. Thus, it is expected that OpenMX can be a useful and powerful theoretical tool for nano-scale material sciences, leading to better and deeper understanding of complicated and useful materials based on quantum mechanics.

The development of OpenMX has been initiated by the Ozaki group in 2000, and from then onward many developers listed in the top page of the manual have contributed for further development of the open source package.

• Total energy and forces by cluster, band, O(N), and low-order scaling methods
• Local density approximation (LDA, LSDA) and generalized gradient approximation (GGA to the exchange-correlation potential
• Norm-conserving pseudopotentials; variationally optimized pseudo-atomic basis functions; fully and scalar relativistic treatment within pseudopotential scheme
• DFT+U methods
• non-collinear DFT; constraint DFT for non-collinear spin and orbital orientation
• Macroscopic polarization by Berry’s phase
• O(N) divide-conquer (DC) method
• O(N) divide-conquer with localized natural orbitals (DC-LNO) method
• O(N) Krylov subspace method
• Parallel eigensolver by ELPA simple, RMM-DIIS, GR-Pulay, Kerker, RMM-DIIS with Kerker’s metric, and RMM-DIIS for Hamiltonian matrix [58] charge mixing schemes
• Exchange coupling parameter; Effective screening medium (ESM) method; Scanning tunneling microscope (STM) simulation
• DFT-D2 and DFT-D3 method for vdW interaction
• Nudged elastic band (NEB) method
• Optical conductivity and dielectric function
• Charge doping; uniform electric field
• Fully and constrained geometry optimization; fully and constrained variable cell optimization
• Electric transport calculations by a non-equilibrium Green’s function (NEGF) method
• NVE ensemble molecular dynamics; NVT and NPT ensemble molecular dynamics by a velocity scaling and the Nose-Hoover methods
• Mulliken, Voronoi, and ESP fitting analysis of charge and spin densities
• Natural population analysis; analysis of wave functions and electron (spin) densities;  dispersion analysis by the band calculation; density of states (DOS) and projected DOS.

References

1. T. Ozaki, Phys. Rev. B. 67, 155108, (2003)
2. T. Ozaki and H. Kino, Phys. Rev. B 69, 195113 (2004)
3. T. Ozaki and H. Kino, Phys. Rev. B 72, 045121 (2005)
4. K. Lejaeghere et al., Science 351, aad3000 (2016)