## About Pyscf

PySCF is a quantum chemistry package written in python. The package aims to provide a simple, light-weight and efficient platform for quantum chemistry calculation and code developing. It is able to efficiently handle medium-size system (around 5000 basis functions, 1000 electrons) on a single SMP node.

## Features

- * Hartree-Fock (up to ~5000 basis)

– Non-relativistic restricted open-shell, unrestricted HF

– scalar relativistic HF

– 2-component relativistic HF

– 4-component relativistic Dirac-Hartree-Fock

– density fitting HF

– Second order SCF

– General JK contraction function - * DFT (up to ~5000 basis)

– Non-relativistic restricted, restricted open-shell, unrestricted Kohn-Sham

– scalar relativistic DFT

– density fitting DFT

– General XC functional evaluator (for Libxc or XcFun)

– General AO evaluator - * TDDFT

– TDHF

– TDDFT

– TDHF gradients

– TDDFT gradients - * General CASCI/CASSCF solver (up to ~2500 basis)

– State-average CASCI/CASSCF

– State-specific CASCI/CASSCF for excited states

– Multiple roots CASCI

– Support DMRG as plugin CI solver to do DMRG-CASSCF

– Support FCIQMC as plugin CI solver to do FCIQMC-CASSCF

– UHF-based UCASSCF

– Density-fitting CASSCF - * MP2 (up to ~200 occupied, ~1000 virtual orbitals)

– RHF-based MP2

– RI-MP2 - * CCSD (up to ~100 occupied, ~800 virtual orbitals)

– canonical CCSD

– canonical CCSD lambda solver

– CCSD 1-particle and 2-particle density matrices

– CCSD gradients - * CCSD(T)

– canonical CCSD(T)

– canonical density matrices

– canonical gradients - * Full CI

– Direct-CI solver for spin degenerated Hamiltonian

– Direct-CI solver for spin non-degenerated Hamiltonian

– 1, and 2-particle transition density matrices

– 1, 2, 3, and 4-particle density matrices - * Gradients

– non-relativistic RHF gradients

– 4-component DHF gradients

– non-relativistic DFT gradients

– non-relativistic CCSD gradients

– non-relativistic TDHF and TDDFT gradients - * Hessian

– non-relativistic RHF hessian

– non-relativistic RKS hessian - * NMR

– non-relativistic RHF NMR shielding

– 4-component DHF NMR shielding

– non-relativistic DFT NMR shielding - * MRPT

– Strongly contracted NEVPT2

– DMRG-NEVPT2

– IC-MPS-PT2 - * Extended systems with periodic boundary condition

– gamma point RHF, UHF, RKS, UKS

– gamma point TDDFT, MP2, CCSD

– PBC RHF, UHF, RKS, UKS with k-point sampling

– PBC CCSD with k-point sampling

– PBC AO integrals

– PBC MO integral transformation

– PBC density fitting - * Solvation effects

– COSMO model for Hartree-Fock, DFT, CASCI, CASSCF and DMRG-CASCI, DMRG-CASSCF - * AO integrals

– Interface to call Libcint library

– 41 types of 1-electron real-GTO integrals

– 29 types of 1-electron spinor-GTO integrals

– 9 types of 2-electron real-GTO integrals

– 33 types of 2-electron spinor-GTO integrals

– 4 types of 3-center 2-electron real-GTO integrals

– 6 types of 3-center 2-electron spinor-GTO integrals

– General basis value evaluator (for numeric integration)

– PBC 1-electron integrals

– PBC 2-electron integrals - * MO integrals

– 2-electron integral transformation for any integrals provided by

Libcint library

– Support for 4-index integral transformation with 4 different orbitals

– PBC 2-electron MO integrals - * Localizer

– Boys

– Edmiston

– Meta-Lowdin

– Natural atomic orbital (NAO)

– Intrinsic atomic orbital (IAO)

– Pipek-Mezey - * D2h symmetry and linear molecule symmetry

– Molecule symmetry detection

– Symmetry adapted basis

– Label orbital symmetry on the fly

– Hot update symmetry information

– Function to symmetrize given orbital space - * Tools

– fcidump

– molden

– cubegen