kccgf

Periodic coupled cluster Green's function for realistic solids

Authors: Tianyu Zhu ([email protected]), Katelyn Laughon, Jason M. Yu

Installation

• Prerequisites

  • PySCF 1.7 or higher, and all dependencies
  • fcdmft (Optional, https://github.com/ZhuGroup-Yale/fcdmft)

• You need to set environment variable PYTHONPATH to export kccgf to Python. E.g. if kccgf is installed in /opt, your PYTHONPATH should be

    export PYTHONPATH=/opt/kccgf:$PYTHONPATH
  

Features

• k-point CCGF (hybrid MPI+OpenMP parallelization)

• k-point CCGF with model order reduction

• k-point CCGF with active-space self-energy correction (CCGF+GW)

QuickStart

To run a periodic CCGF calculation, use the following steps:

1. Run periodic HF calculation and save the GDF integrals. Example: /kccgf/examples/silicon/HF/si_khf.py.
2. Run periodic CCSD calculation and save the CCSD amplitudes and MO integals (ERIS). Read GDF integrals and HF results from the last step to save time. Example: /kccgf/examples/silicon/CCSD/si_ccsd.py.
3. Run periodic CCGF calculation, either in parallel or using batch serial jobs. Read CCSD amplitudes and ERIS from last step to save time. For full CCGF, see example: /kccgf/examples/silicon/CCGF/si_ccgf.py (use submit.sh to submit batch jobs and gather_gf.py to collect GF and DOS). For MOR-CCGF, see example: /kccgf/examples/silicon/MOR/.

To run a MOR-CCGF+MOR (active-space self-energy correction), follow these steps:

1. Run periodic HF (same as in full CCGF Step 1).
2. Run G0W0@HF calculation and save GW self-energy files. Example: /kccgf/examples/silicon/MOR-CCGF+GW/GW/si_gw.py.
3. Run periodic CAS-CCSD calculation and save the CCSD amplitudes and MO integals (ERIS). Copy vxc.h5 and sigma_imag.h5 from GW folder to CAS-CCSD folder to enable loading GW results. Example: /kccgf/examples/silicon/MOR-CCGF+GW/CAS-CCSD/si_ccsd.py.
4. Run MOR-CCGF+GW calculation, either in parallel or using batch serial jobs. Read CCSD amplitudes and ERIS as well as GW self-energy from Step 2 and 3 to save time. See example: /kccgf/examples/silicon/MOR-CCGF+GW/CAS-CCGF+GW/si_cc_gw.py. Use submit.sh to submit batch jobs and si_gather_gf.py to collect GF and DOS.

References

• K. Laughon, J. M. Yu, and T. Zhu, arXiv:2208.07478