Software

In the course of the work of the department there were several scientific codes written, that are made available to the community as open-source.

 

NECI

NECI is a state-of-the-art implementation of the Full Configuration Interaction Quantum Monte Carlo (FCIQMC) algorithm, a method based on a stochastic application of the Hamiltonian matrix on a sparse sampling of the wave function. The program utilizes a very powerful parallelization and scales efficiently to more than 24 000 central processing unit cores. To access the code or documentation just click the respective links.
 

TChInt

TCHInt is a library for efficient parallelised calculations of transcorrelation Hamiltonian integrals. It is designed to be user-friendly, portable and easy interfaceable. TCHInt can be used either as a library interfaced to other programs, or as a standalone program to generate integral files for similarity-transformed Hamiltonians. Documentation can be accessed here. Currently, the source code is not publicly available, but will soon be on GitHub. If you are interested, please contact one of the developers.
 

OpenMolcas

OpenMolcas is an internationally developed open-source quantum chemistry software package that supports a variety of state-of-the art single and multi-reference methods for computing the electronic structure of challenging chemical systems. OpenMolcas is one of the leading platforms to perform multi-configurational SCF calculations at the Complete, Restricted, and Generalized Active Space (XAS-SCF, X = C, R, G) level. Our research focuses on developing stochastic method for the optimization of prohibitively large active space wave function. Via the Stochastic-CASSCF method active spaces as large as CAS(40,40) are routinely tackled. Via Stochastic-GASSCF MRCI like wave functions with up to 100 electrons and 150 orbitals have been optimized. The OpenMolcas code and documentation are available from the web.

 

ElemCo.jl

ElemCo.jl is a Julia-based quantum chemistry package implementing a wide range of electron-correlation methods, with a particular focus on coupled-cluster theory. Alongside standard closed- and open-shell CCSD and CCSD(T), it implements the Distinguishable Cluster approximation (DCSD) and its many extensions - including a tensor-decomposed SVD-DC-CCSDT that brings full triples within reach at reduced cost - along with equation-of-motion methods for excited states and full and selected configuration interaction (CIPHI). Molecular integrals are obtained from a FCIDUMP file or computed directly through an interface to libcint, with density fitting available throughout. Input files can be generated, and molecular orbitals visualized, using JLmol, a companion graphical application also developed in the group. The code and documentation are available at https://github.com/fkfest/ElemCo.jl and https://elem.co.il, respectively.

 

JLmol

JLmol is a molecular structure viewer and editor, available as a browser application and as a cross-platform Electron desktop app. It combines 3D visualization (via JSmol) with a 2D structure editor (JSME) and direct structure lookup from the PubChem database, and can generate and run ElemCo.jl calculations directly from a loaded structure or FCIDUMP file, including visualization of the resulting molecular orbitals. Try the browser version at "https://app.jlmol.com", or get the code and desktop installers from "https://github.com/fkfest/jlmol".