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QuantumChemistry

 FullCI
 A configuration interaction (CI) method, operating on all of the orbitals Calling Sequence FullCI(molecule, options) Parameters

 molecule - list of lists; each list has 4 elements, the string of an atom's symbol and atom's x, y, and z coordinates options - (optional) equation(s) of the form option = value where option is one of symmetry, unit, davidson_only, lindep,  max_memory, max_cycle, max_space, conv_tol, nuclear_gradient, return_rdm, populations, level_shift, pspace_size, conv_tol_hf, diis_hf, diis_space_hf, diis_start_cycle_hf, direct_scf_hf, direct_scf_tol_hf, level_shift_hf, max_cycle_hf, nuclear_gradient_hf, populations_hf  Description

 • FullCI, also known as full configuration interaction (FCI), performs a configuration interaction calculation over all of the molecular orbitals (MOs).  The method solves the Schrödinger equation exactly in the selected basis set.
 • FullCI scales exponentially in floating-point operations and memory with the number of electrons. Outputs

The table of following contents:

 ${t}\left[{\mathrm{e_tot}}\right]$ - float -- total electronic energy of the system ${t}\left[{\mathrm{e_corr}}\right]$ - float -- the difference between the FCI energy and the Hartree-Fock energy ${t}\left[{\mathrm{mo_coeff}}\right]$ - Matrix -- coefficients expressing natural molecular orbitals (columns) in terms of atomic orbitals (rows) ${t}\left[{\mathrm{mo_occ}}\right]$ - Vector -- molecular (natural) orbital occupations ${t}\left[{\mathrm{aolabels}}\right]$ - Vector -- string label for each atomic orbital consisting of the atomic symbol and the orbital name ${t}\left[{\mathrm{ci_coeff}}\right]$ - Matrix -- a matrix of CI coefficients whose rows represent α-spin coefficient indices and columns represent β-spin coefficient indices ${t}\left[{\mathrm{rdm1}}\right]$ - Matrix -- one-particle reduced density matrix (1-RDM) in the molecular-orbital (MO) representation ${t}\left[{\mathrm{rdm2}}\right]$ - Array -- two-particle reduced density matrix (2-RDM) in the molecular-orbital (MO) representation ${t}\left[{\mathrm{dipole}}\right]$ - Vector -- dipole moment according to its x, y and z components ${t}\left[{\mathrm{populations}}\right]$ - Matrix -- atomic-orbital populations ${t}\left[{\mathrm{charges}}\right]$ - Vector -- atomic charges from the populations ${t}\left[{\mathrm{nuclear_gradient}}\right]$ - Matrix -- analytical nuclear gradient Options

 • basis = string -- name of the basis set.  See Basis for a list of available basis sets.  Default is "sto-3g".
 • spin = nonnegint -- twice the total spin S (= 2S). Default is 0.
 • charge = nonnegint -- net charge of the molecule. Default is 0.
 • symmetry = string/boolean -- is the Schoenflies symbol of the abelian point-group symmetry which can be one of the following:  D2h, C2h, C2v, D2, Cs, Ci, C2, C1. true finds the appropriate symmetry while false (default) does not use symmetry.
 • unit = string -- "Angstrom" or "Bohr". Default is "Angstrom".
 • max_memory = posint -- allowed memory in MB. Default is 4000.
 • conv_tol = float -- converge threshold. Default is ${10}^{-10}.$
 • nuclear_gradient = boolean -- option to return the analytical nuclear gradient if available. Default is false.
 • return_rdm = string -- options to return the 1-RDM and/or 2-RDM: "none", "rdm1", "rdm1_and_rdm2". Default is "rdm1".
 • populations = string -- atomic-orbital population analysis: "Mulliken" and "Mulliken/meta-Lowdin". Default is "Mulliken".
 • davidson_only = boolean -- use the Davidson diagonalization method to find the ground-state eigenvalues.
 • level_shift = float -- level shift for the Davidson diagonalization. Default is ${10}^{-3}$.
 • lindep = float -- linear dependence threshold for AH solver. Default is ${10}^{-10}$.
 • max_cycle = posint -- max number of iterations. Default is 50.
 • max_space = posint -- space size to hold trial vectors. Default is 12.
 • pspace_size = posint -- size of Hamiltonian to improve Davidson preconditioner. Default is 50.
 • Attributes for Hartree Fock:
 • conv_tol_hf = float -- converge threshold. Default is ${10}^{-10}.$
 • diis_hf = boolean -- whether to employ diis. Default is true.
 • diis_space_hf = posint -- diis's space size. By default, 8 Fock matrices and error vectors are stored.
 • diis_start_cycle_hf = posint -- the step to start diis. Default is 1.
 • direct_scf_hf = boolean -- direct SCF in which integrals are recomputed is used by default.
 • direct_scf_tol_hf = float -- direct SCF cutoff threshold. Default is ${10}^{-13}.$
 • level_shift_hf = float/int -- level shift (in au) for virtual space. Default is $0.$
 • max_cycle_hf = posint -- max number of iterations. Default is 50.
 • nuclear_gradient_hf = boolean -- option to return the analytical nuclear gradient. Default is false.
 • populations_hf = string -- atomic-orbital population analysis: "Mulliken" and "Mulliken/meta-Lowdin". Default is "Mulliken". References

 1 P. J. Knowles and N.  C. Handy, Chem. Phys. Lett. 111, 315-321 1984. "A  new  determinant-based  full  configuration  interaction  method"
 2 J. Olsen, P. Jørgensen, and J. Simons, Chem. Phys. Lett. 169, 463-472 (1990). "Passing the one-billion limit in full configuration-interaction (FCI) calculations"
 3 T. Helgaker, P. Jørgensen, and J. Olsen, Molecular Electronic-Structure Theory (John Wiley & Sons, New York, 2000).
 4 A. Szabo and N. S. Ostlund, Modern Quantum Chemistry: Introduction to Advanced Electronic Structure Theory (Dover Books, New York, 1996). Examples

 > $\mathrm{with}\left(\mathrm{QuantumChemistry}\right):$

An full CI calculation of the  molecule

 >
 ${\mathrm{molecule}}{≔}\left[\left[{"H"}{,}{0}{,}{0}{,}{0}\right]{,}\left[{"F"}{,}{0}{,}{0}{,}{0.95000000}\right]\right]$ (1)
 >
 ${\mathrm{table}}{}\left({\mathrm{%id}}{=}{18446744821133004766}\right)$ (2)
 >