ctseg

Spec sheet

Purpose

CTSEG is a TRIQS-based hybridization-expansion segment-picture solver for quantum impurities coupled to an external bath.Read 11 Oct 2026 · triqs.github.io

Free plan

YesRead 24 Sep 2026 · triqs.github.io

Support

The TRIQS project points users to GitHub Discussions and GitHub issues for help with problems.Read 11 Oct 2026 · triqs.github.io

License

TRIQS, the software ecosystem CTSEG is based on, is free software distributed under the GPL license.Read 11 Oct 2026 · triqs.github.io

Algorithm

The double expansion samples powers of the hybridization function and perpendicular spin-spin interaction to measure observables such as the Green’s function.Read 11 Oct 2026 · triqs.github.io

Authors

The TRIQS/ctseg solver was written by N. Kavokine and O. Parcollet, with contributions from H. Lu and N. Wentzell.Read 11 Oct 2026 · triqs.github.io

Delivery mode

desktopRead 24 Sep 2026 · triqs.github.io

Dependency

Building CTSEG from source requires the TRIQS library, and CTSEG must match TRIQS in its major and minor version numbers.Read 11 Oct 2026 · triqs.github.io

Installation

The project documents Ubuntu 24.04 Debian packages, Linux and OSX Anaconda packages, Docker, and building from source.Read 11 Oct 2026 · triqs.github.io

Interactions

It supports possibly retarded density-density and spin-spin interactions on the impurity.Read 11 Oct 2026 · triqs.github.io

Measurement constraint

With perpendicular spin-spin interactions, the improved self-energy estimator is available only when the spin-spin interactions are rotationally invariant.Read 11 Oct 2026 · triqs.github.io

Measurements

Documented observables include imaginary-time Green’s functions, self-energy estimators, densities, density correlations, two-particle Green’s functions, state histograms, and perturbation-order histograms.Read 11 Oct 2026 · triqs.github.io

Offline access

YesRead 24 Sep 2026 · triqs.github.io

Orbital limit

The perpendicular spin-spin expansion is supported only for a single orbital; for multiple orbitals, only expansion in the hybridization function is possible.Read 11 Oct 2026 · triqs.github.io

Performance

Under its supported interaction restrictions, CTSEG provides better performance than the generic CTHYB solver.Read 11 Oct 2026 · triqs.github.io

Reproducibility

The installation guide recommends stable releases of TRIQS and its applications for reproducible scientific calculations.Read 11 Oct 2026 · triqs.github.io

Plans and prices

Every ctseg plan and price →

Where Specifiction places it

• Physics Simulation Software#59 of 897.5