green-mbtools

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===================

Python Tool Suite for Green's-function-based many-body calculations using Green Software Package.

Package contains two main modules:

• mint (Mean-feald INput generation Toolkit): generates input files for Green/WeakCoupling using PySCF, ASE and SPGLib
• pesto (Post-processing Evaluation Software TOols): provides access to various post-processing tools such as analytical continuation, and Mulliken analysis.

Installation

• To install the green-mbtools binary package simply execute:

pip install green-mbtools

• To build from sources download the source code either from github or from PyPI and run:

python -m build

This will automatically build the Nevanlinna and Caratheodory extensions, which are written in C++.

Dependencies:

1. Python packages: numpy, scipy, h5py, green-ac, pyscf, ase, spglib, irbasis, cvxpy, and baryrat.
2. C++ libraries: Eigen, GMP, MPFR
3. pytest for testing
4. Maxent external C++ librar needs to be built separately to run analytic continuation tasks using the maxent method.

Features

• Generate input for Green/WeakCoupling.
• Compute molecular/natural orbitals.
• Mulliken analyasis based on symmetrical atomic orbitals.
• Fourier transformation between real and reciprocal space.
• Fourier transformation between imaginary-time and Matsuabara frequency domain on IR grids.
• Wannier interpolation
• Maxent analytical continuation (External C++ library required: https://github.com/CQMP/Maxent)
• Nevanlinna analytical continuation, based on Fei et.al. Phys. Rev. Lett. 126, 056402 (2021).
• PES analytical continuation, based on Phys. Rev. B 107, 075151 (2023).
• Caratheodory analytical continuation for complex valued matrices (External C++ library in Caratheodory, authored by Fei et.al. Phys. Rev. B 104, 165111 (2021).

To-Do-List

• Migrate to newer IR grid format
• Improved README and documentation on where to find examples (perhaps a sub-README in the examples folder),
• (for current implementation of Nevanlinna) re-integrate Hardy optimization
• Fix examples/winter*.py: The original example for Silicon has been modified to Hydrogen (for which test data is available). The high-symmetry points in the interpolation need to be readjusted accordingly.

Contirbutions to the code

• Most of the pesto source code was written by @cnyeh
• Nevanlinna analytic continuation was implemented by @jianiOnly
• Clean up and packaging of the code and extension modules, including Nevanlinna and Caratheodory, was performed by by @gauravharsha
• ES analytic continuation implemented by @gauravharsha
• Example for spaghetti diagrams for occupation numbers added by @pavel-po
• C++ wrapper to GMP and MPFR float numbers and packaging @iskakoff
• Green/WeakCoupling input generation @cnyeh and @iskakoff