compute the molecular orbital (MO) occupations
MOOccupations(molecule, method, options)
list of lists; each list has 4 elements, the string of an atom's symbol and atom's x, y, and z coordinates
(optional) method = name/procedure where name is one of 'HartreeFock' (default), 'DensityFunctional','ActiveSpaceCI', 'ActiveSpaceSCF', 'CoupledCluster', 'FullCI','MP2', 'Variational2RDM', 'Parametric2RDM','ContractedSchrodinger'
(optional) equation(s) of the form option = value where option is any valid option of the chosen method
MOOccupations computes the occupations of the molecular orbitals (MOs).
The procedure returns the MO occupations as a Vector whose n-th element gives the occupation of the n-th MO.
The MO occupations are the eigenvalues of the one-electron reduced density matrix (1-RDM), known as the natural occupations.
The default method is 'HartreeFock' method whose correlation energy is 0.
The result depends upon the chosen molecule, method, and basis set among other options such as charge, spin, and symmetry.
Because the methods employ Maple cache tables, the procedure only computes the MO occupations if they have not been previously computed by calling the method directly or indirectly through another property.
Computation of the MO occupations of the hydrogen fluoride HF molecule with the Hartree-Fock method
molecule ≔ H,0,0,0,F,0,0,0.95;
output_hf ≔ MOOccupationsmolecule, method='HartreeFock';
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