About ModEST

What ModEST is

Mod ular E lectronic S tructure T oolkit (ModEST) is the electronic-structure extension pack to the TRIQS library. It provides the tooling needed to build generic quantum-embedding calculations — DMFT and its extensions — in direct connection to electronic-structure methods such as density-functional theory (DFT) and many-body perturbation theory (MBPT).

ModEST is aimed at two audiences: electronic-structure practitioners who want to plug a DFT (or GW) backend into a DMFT loop, and DMFT practitioners who want a uniform interface across different DFT codes, tight-binding models, and embedding scenarios.

What ModEST does

ModEST is organized around three primary use cases of quantum embedding calculations:

  1. Tight-binding — a tight-binding model is derived from a DFT band structure (typically through Wannier90), and a DMFT calculation is built directly on top of that dispersion. This is the lightest-weight entry point and is one flavor of dynamical mean-field calculations in combination with electronic structure.

  2. Charge self-consistent DFT+DMFT (CSC) — ModEST exposes interfaces to several DFT codes (VASP, Quantum ESPRESSO, Wien2k, Elk, AbInit, Wannier90), making it possible to write charge self-consistent DFT+DMFT implementations in which the electronic density is updated by the DMFT impurity solution and fed back into the DFT cycle.

  3. Library mode — ModEST is fundamentally a library that other projects can consume. A notable example is CoQui, which targets GW+EDMFT in conjunction with TRIQS.

Across all three modes the same primitives are reused: load a one-body-elements object, describe the correlated subspace and its mapping to impurities with an embedding, and compute k-summed observables (local Green’s function, charge self-consistency correction). Double counting, interaction Hamiltonians, spectral-function post-processing, and HDF5 checkpointing complete the picture.

To see ModEST’s building blocks used end-to-end, continue to the User guide.