Electronic structure E-CAM modules V
Creators: name: Mendonça, Ana Catarina
name: Ruggeri, Michele
name: Coretti, Alessandro
Publisher: name: Zenodo
Year: 2021

description: The modules in this report are part of larger software packages and are intended to extend their features and functionalities. In particular, four of the modules presented here are part of the QMCPack package, an open source Quantum Monte Carlo (QMC) package for ab initio electronic structure calculations. QMC methods are a class of ab initio, stochastic techniques for the study of quantum systems. While QMC simulations are computationally expensive, they have the advantage of being accurate, fully ab initio and scalable to a large number of core with limited memory requirements. These features make QMC methods a valuable tool to assess the accuracy of Density Functional Theory (DFT) computations, which are widely used in the fields of condensed matter physics, quantum chemistry and material science. We present in this document four modules that are interfaces between QMCPack and a software commonly used in electronic structure computations, Quantum Espresso. These are QMCQEPack, ESInterfaceBase, ESHDF5Interface and ESPWSCFInterface. Such interfaces can be used to establish an automated, black box workflow to benchmark and validate the results of DFT simulations involving physical systems of interest which can have applications for industry, e.g. in the study of metal-ion or water-carbon interfaces. Three of the modules presented here were written as part of the Electronic-Structure Library (ESL) project. Electronic structure simulations are a fundamental tool in the study of a large array of problems in condensed matter and quantum chemistry, which have a large range of applications in several fields of research, from condensed matter physics and material science to quantum chemistry to biology and nanomedicine. Theoretical studies in electronic structure are mostly performed independently by separate research groups, employing a wide array of different methods (such as but not limited to DFT classical, quantum Monte Carlo and various quantum chemistry methods), each implemented in different software’s and employing different data standards. The goal of the ESL initiative is to provide a library of standard, high quality software for electronic structure computations, to facilitate sharing of data, results and ultimately knowledge between different research group, and to allow scientists to focus more on their research topics than coding and software engineering. Herein we present three software modules from the ESL produced during the ESDW: Integration of ESL modules into electronic-structure codes held at CECAM Headquarters in Lausanne on 17-28 February 2020. These are Integration of ELSI-RCI in DFTB+, Integration of Libxc in FHI-AiMS and PSolver in SIESTA and Octopus. Finally, theMaZe code is presented in this deliverable. MaZe stands for theMass-Zero constrained molecular dynamics approach discussed in Phys. Chem. Chem. Phys., 22:10775–10785, 2020. This method enforces, at each time step, the Born-Oppenheimer condition that the system relaxes instantaneously to the ground state through the formalism of massless constraints. The adiabatic separation between the degrees of freedom is enforced rigorously, and the algorithmis symplectic and time-reversible in both physical and additional set of degrees of freedom. The code is intended for condensed matter physicists and for material scientists and it can be used for various purposes related to the subject. The main goal of the software is to produce particles trajectories to be analyzed in post-production by means of external software. Three modules are presented here for theMaZe code: the MaZe for OF-DFT, the MaZe for OF-DFT (HPC version) and the NLCG for OF-DFT. A short description is written for each module, followed by a link to the respectiveMerge-Request on the GitLab service of E-CAM. These merge requests contain detailed information about the code development, testing and documentation of the modules. As this deliverable is the last one of its series, a section on the overall impact of the results achieved within the Workpackage Electronic Structure was also included.