pyscfad.cc.rccsd.RCCSDLite#

class pyscfad.cc.rccsd.RCCSDLite(mf, mo_coeff=None, mo_occ=None, nocc=None, **kwargs)[source]#

Bases: object

Restricted CCSD for the lightweight molecule and mean-field objects.

Parameters:

  • mf (SCFLite) – Converged SCFLite (or SCFPad) mean field.

  • mo_coeff (Array | None) – MO coefficients. Defaults to mf.mo_coeff.

  • mo_occ (Array | None) – MO occupations. Defaults to mf.mo_occ.

  • nocc (int | None) – Number of doubly occupied orbitals. Static; inferred from the molecular electron count when not given, which requires that count to be concrete. For a padded molecule it may exceed the true occupation – as a batch of padded molecules requires – and the extra occupied slots are then filled with fake orbitals.

Attributes:

  • diis (str | None) – Amplitude mixer, 'diis' for Pulay’s DIIS (the default), 'anderson' for Anderson mixing, or None for the bare iterations.

  • conv_tol_implicit_diff – Convergence threshold of the GMRES solve of the implicit derivative.

  • max_cycle_implicit_diff – Maximum number of GMRES iterations.

  • restart_implicit_diff – Krylov subspace size of the GMRES solve.

Methods

amplitude_equation(t1, t2, eris)

ao2mo([mo_coeff])

ccsd([t1, t2, eris])

dump_flags([verbose])

energy([t1, t2, eris])

init_amps(eris)

MP2 amplitudes, the initial guess of the CCSD iterations.

init_diis(amps)

Amplitude mixer.

kernel([t1, t2, eris])

run_diis(amps, amps_last, diis)

update_amps(t1, t2, eris)