FermiPairing.jl

Traditional and novel quantum chemistry methods for approximating exact energies of the reduced Bardeen--Cooper--Schrieffer (BCS) Hamiltonian, a model Hamiltonian describing fermion pairs. Can be extended to any Hamiltonian made from operators that follow su(2) commutation relations.

Methods

• Doubly occupied configuration interaction (DOCI).
• Particle-hole configuration interaction (CI) based on Hartree--Fock (HF).
• Antisymmetrized geminal power (AGP).
• Linear combinations of AGP (LC-AGP) as non-orthogonal configuration interaction (NOCI).
• LC-AGP as non-orthogonal multi-configuration self-consistent field (NO-MCSCF).
• Binary tree state (BTS).
• Linear combinations of BTS (LC-BTS) as NOCI.
• LC-BTS as NO-MCSCF.

Install

There are two ways of adding Julia packages, either using the add command or the dev command. Use the Julia REPL, enter Pkg by pressing ] and write the command below.

pkg> add "git@github.com:rishabdchem/FermiPairing.jl.git"

Or clone this repo to your local machine, go to the Julia Pkg REPL, and write the command below.

pkg> dev path/to/FermiPairing.jl

References

1. Dukelsky, Pittel, Sierra. Colloquium: Exactly solvable Richardson-Gaudin models for many-body quantum systems. Rev. Mod. Phys. 76, 643 (2004) article preprint

2. Khamoshi, Henderson, Scuseria. Efficient evaluation of AGP reduced density matrices. J. Chem. Phys. 151, 184103 (2019) article preprint

3. Dutta, Henderson, Scuseria. Geminal replacement models based on AGP. J. Chem. Theory Comput. 16, 6358 (2020) article preprint

4. Dutta, Chen, Henderson, Scuseria. Construction of linearly independent non-orthogonal AGP states. J. Chem. Phys. 154 114112 (2021)
   article preprint

5. Dutta, Gao, Khamoshi, Henderson, Scuseria. Correlated pair ansatz with a binary tree structure. preprint