CCWavefunction

class psi4.core.CCWavefunction

Bases: Wavefunction

Specialized Wavefunction used by the ccenergy, cceom, ccgradient, etc. modules.

Methods Summary

get_amplitudes(self)	Get dict of converged T amplitudes.
total_index(self, i, h)	Map an index (i) within irrep (h) to its energy-sorted index among all roots.

Methods Documentation

get_amplitudes(self: psi4.core.CCWavefunction) → dict[str, psi4.core.Matrix]

Get dict of converged T amplitudes.

Returns:

• amps (dict (spacestr, SharedMatrix)) – spacestr is a description of the amplitude set using the following conventions.

  • I,J,K -> alpha occupied

  • i,j,k -> beta occupied

  • A,B,C -> alpha virtual

  • a,b,c -> beta virtual

• The following entries are stored in the amps, depending on the reference type

• RHF (tIA, tIjAb)

• UHF (tIA, tia, tIjAb, tIJAB, tijab)

• ROHF (tIA, tia, tIjAb, tIJAB, tijab)

Examples

RHF T1 diagnostic = sqrt(sum_ia (T_ia * T_ia)/nelec) >>> mol = “”” … 0 1 … Ne 0.0 0.0 0.0 … symmetry c1””” >>> e, wfn = psi4.energy(“CCSD/cc-pvdz”, return_wfn=True) >>> t1 = wfn.get_amplitudes()[‘tia’].to_array() >>> t1_diagnostic = np.sqrt(np.dot(t1.ravel(),t1.ravel())/ (2 * wfn.nalpha()) >>> t1_diagnostic == psi4.variable(“CC T1 DIAGNOSTIC”) True

Warning

Symmetry free calculations only (nirreps > 1 will cause error)

Warning

No checks that the amplitudes will fit in core. Do not use for proteins

total_index(self: psi4.core.CCWavefunction, i: int, h: int) → int

Map an index (i) within irrep (h) to its energy-sorted index among all roots.