When entering the field of highly specialized scientific disciplines, software development tends to follow rules shared and agreed upon within that specific scientific community, which, however, are often not reusable by others. The goal of TREX is to reimplement the algorithms in a domain-agnostic way such that HPC experts can easily provide the most efficient implementation for exascale hardware.

Within the TREX project, state-of-the-art programs for quantum Monte Carlo (QMC) calculations are analysed to identify key algorithms to be then implemented in human-readable, open-source software QMCkl & TREXIO libraries. The libraries are further optimized for future exascale supercomputers by computer scientists of the TREX project. The QMC codes within TREX are at different stages of software development but are all algorithmically extremely advanced and uniquely powerful in the landscape of electronic structure methods.

QMCkl Code


The QMCkl library aims at providing a high-performance implementation of the main kernels of Quantum Monte Carlo methods.



The TREXIO library defines a standard format for storing wave function parameters, together with a C-compatible API such that it can be easily used in any programming language.