LibOMM : Orbital Minimization Method Library

Purpose

The library LibOMM solves the Kohn-Sham equation as a generalized eigenvalue problem for a fixed Hamiltonian. It implements the orbital minimization method (OMM), which works within a density matrix formalism. The basic strategy of the OMM is to find the set of Wannier functions (WFs) describing the occupied subspace by direct unconstrained minimization of an appropriately-constructed functional. The density matrix can then be calculated from the WFs. The solver is usually employed within an outer self-consistency (SCF) cycle. Therefore, the WFs resulting from one SCF iteration can be saved and then re-used as the initial guess for the next iteration.

More information on the module’s documentation can be found here, and the source code is available from the E-CAM Gitlab here. The algorithms and implementation of the library are described in https://arxiv.org/abs/1312.1549v1.

This module is an effort from the Electronic Structure Library Project (ESL), and it was initiated during an E-CAM Extended Software Development Workshop in Zaragoza in June 2016. This and other codes revolved around the broad theme of solvers, were recently reported in Deliverable D2.1.: Electronic structure E-CAM modules I, available for download and consultation here.

Practical application and exploitation of the module

libOMM is one of the libraries supported and enhanced by the Electronic Structure Infrastructure ELSI [1], which in turn is interfaced with the DGDFT, FHI-aims, NWChem, and SIESTA codes.

[1] The electronic structure infrastructure ELSI  provides and enhances scalable, open-source software library solutions for electronic structure calculations in materials science, condensed matter physics, chemistry, molecular biochemistry, and many other fields [https://arxiv.org/abs/1705.11191v1].

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