quantum_package/src/Dets

===========
Dets Module
===========

This module contains the determinants of the CI wave function.

H is applied on the list of generator determinants. Selected determinants
are added into the *H_apply buffer*. Then the new wave function is
constructred as the concatenation of the odl wave function and
some determinants of the H_apply buffer. Generator determinants are built
as a subset of the determinants of the wave function.


Assumptions
===========

.. Do not edit this section. It was auto-generated from the
.. NEEDED_MODULES file.

* The MOs are orthonormal
* All the determinants have the same number of electrons
* The determinants are orthonormal
* The number of generator determinants <= the number of determinants
* All the determinants in the H_apply buffer are supposed to be different from the 
  wave function determinants
* All the determinants in the H_apply buffer are supposed to be unique


Needed Modules
==============

.. Do not edit this section. It was auto-generated from the
.. NEEDED_MODULES file.

* `AOs <http://github.com/LCPQ/quantum_package/tree/master/src/AOs>`_
* `BiInts <http://github.com/LCPQ/quantum_package/tree/master/src/BiInts>`_
* `Bitmask <http://github.com/LCPQ/quantum_package/tree/master/src/Bitmask>`_
* `Electrons <http://github.com/LCPQ/quantum_package/tree/master/src/Electrons>`_
* `Ezfio_files <http://github.com/LCPQ/quantum_package/tree/master/src/Ezfio_files>`_
* `Hartree_Fock <http://github.com/LCPQ/quantum_package/tree/master/src/Hartree_Fock>`_
* `MonoInts <http://github.com/LCPQ/quantum_package/tree/master/src/MonoInts>`_
* `MOs <http://github.com/LCPQ/quantum_package/tree/master/src/MOs>`_
* `Nuclei <http://github.com/LCPQ/quantum_package/tree/master/src/Nuclei>`_
* `Output <http://github.com/LCPQ/quantum_package/tree/master/src/Output>`_
* `Utils <http://github.com/LCPQ/quantum_package/tree/master/src/Utils>`_

Documentation
=============

.. Do not edit this section. It was auto-generated from the
.. NEEDED_MODULES file.

`copy_h_apply_buffer_to_wf <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/H_apply.irp.f#L/subroutine copy_H_apply_buffer_to_wf/;">`_
  Copies the H_apply buffer to psi_coef. You need to touch psi_det, psi_coef and N_det
  after calling this function.

`fill_h_apply_buffer_no_selection <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/H_apply.irp.f#L/subroutine fill_H_apply_buffer_no_selection(n_selected,det_buffer,Nint,iproc)/;">`_
  Fill the H_apply buffer with determiants for CISD

`h_apply_buffer_allocated <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/H_apply.irp.f#L/BEGIN_PROVIDER [ logical, H_apply_buffer_allocated ]/;">`_
  Buffer of determinants/coefficients/perturbative energy for H_apply.
  Uninitialized. Filled by H_apply subroutines.

`h_apply_threshold <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/H_apply.irp.f#L/BEGIN_PROVIDER [ double precision, H_apply_threshold ]/;">`_
  Theshold on | <Di|H|Dj> |

`resize_h_apply_buffer <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/H_apply.irp.f#L/subroutine resize_H_apply_buffer(new_size,iproc)/;">`_
  Undocumented

`cisd_sc2 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/SC2.irp.f#L/subroutine CISD_SC2(dets_in,u_in,energies,dim_in,sze,N_st,Nint,convergence)/;">`_
  CISD+SC2 method              :: take off all the disconnected terms of a CISD (selected or not)
  .br
  dets_in : bitmasks corresponding to determinants
  .br
  u_in : guess coefficients on the various states. Overwritten
  on exit
  .br
  dim_in : leftmost dimension of u_in
  .br
  sze : Number of determinants
  .br
  N_st : Number of eigenstates
  .br
  Initial guess vectors are not necessarily orthonormal

`repeat_excitation <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/SC2.irp.f#L/subroutine repeat_excitation(key_in,key_1,key_2,i_ok,Nint)/;">`_
  Undocumented

`connected_to_ref <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/connected_to_ref.irp.f#L/integer function connected_to_ref(key,keys,Nint,N_past_in,Ndet)/;">`_
  Undocumented

`det_is_not_or_may_be_in_ref <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/connected_to_ref.irp.f#L/logical function det_is_not_or_may_be_in_ref(key,Nint)/;">`_
  If true, det is not in ref
  If false, det may be in ref

`is_in_wavefunction <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/connected_to_ref.irp.f#L/logical function is_in_wavefunction(key,Nint,Ndet)/;">`_
  Undocumented

`key_pattern_not_in_ref <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/connected_to_ref.irp.f#L/BEGIN_PROVIDER [ logical, key_pattern_not_in_ref, (-128:127,N_int,2) ]/;">`_
  Min and max values of the integers of the keys of the reference

`davidson_converged <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/davidson.irp.f#L/subroutine davidson_converged(energy,residual,wall,iterations,cpu,N_st,converged)/;">`_
  True if the Davidson algorithm is converged

`davidson_criterion <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/davidson.irp.f#L/BEGIN_PROVIDER [ character(64), davidson_criterion ]/;">`_
  Can be : [  energy  | residual | both | wall_time | cpu_time | iterations ]

`davidson_diag <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/davidson.irp.f#L/subroutine davidson_diag(dets_in,u_in,energies,dim_in,sze,N_st,Nint,iunit)/;">`_
  Davidson diagonalization.
  .br
  dets_in : bitmasks corresponding to determinants
  .br
  u_in : guess coefficients on the various states. Overwritten
  on exit
  .br
  dim_in : leftmost dimension of u_in
  .br
  sze : Number of determinants
  .br
  N_st : Number of eigenstates
  .br
  iunit : Unit number for the I/O
  .br
  Initial guess vectors are not necessarily orthonormal

`davidson_diag_hjj <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/davidson.irp.f#L/subroutine davidson_diag_hjj(dets_in,u_in,H_jj,energies,dim_in,sze,N_st,Nint,iunit)/;">`_
  Davidson diagonalization with specific diagonal elements of the H matrix
  .br
  H_jj : specific diagonal H matrix elements to diagonalize de Davidson
  .br
  dets_in : bitmasks corresponding to determinants
  .br
  u_in : guess coefficients on the various states. Overwritten
  on exit
  .br
  dim_in : leftmost dimension of u_in
  .br
  sze : Number of determinants
  .br
  N_st : Number of eigenstates
  .br
  iunit : Unit for the I/O
  .br
  Initial guess vectors are not necessarily orthonormal

`davidson_iter_max <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/davidson.irp.f#L/BEGIN_PROVIDER [ integer, davidson_iter_max ]/;">`_
  Max number of Davidson iterations

`davidson_sze_max <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/davidson.irp.f#L/BEGIN_PROVIDER [ integer, davidson_sze_max ]/;">`_
  Max number of Davidson sizes

`davidson_threshold <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/davidson.irp.f#L/&BEGIN_PROVIDER [ double precision, davidson_threshold ]/;">`_
  Can be : [  energy  | residual | both | wall_time | cpu_time | iterations ]

`det_search_key <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/integer*8 function det_search_key(det,Nint)/;">`_
  Return an integer*8 corresponding to a determinant index for searching

`n_det <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ integer, N_det ]/;">`_
  Number of determinants in the wave function

`n_det_max_jacobi <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ integer, N_det_max_jacobi ]/;">`_
  Maximum number of determinants diagonalized my jacobi

`n_states <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ integer, N_states ]/;">`_
  Number of states to consider

`psi_average_norm_contrib <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ double precision, psi_average_norm_contrib, (N_det) ]/;">`_
  Contribution of determinants to the state-averaged density

`psi_average_norm_contrib_sorted <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/&BEGIN_PROVIDER [ double precision, psi_average_norm_contrib_sorted, (N_det) ]/;">`_
  Wave function sorted by determinants contribution to the norm (state-averaged)

`psi_coef <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ double precision, psi_coef, (psi_det_size,N_states) ]/;">`_
  The wave function coefficients. Initialized with Hartree-Fock if the EZFIO file
  is empty

`psi_coef_sorted <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/&BEGIN_PROVIDER [ double precision, psi_coef_sorted, (N_det,N_states) ]/;">`_
  Wave function sorted by determinants contribution to the norm (state-averaged)

`psi_coef_sorted_bit <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/&BEGIN_PROVIDER [ double precision, psi_coef_sorted_bit, (N_det,N_states) ]/;">`_
  Determinants on which we apply <i|H|psi> for perturbation.
  o They are sorted by determinants interpreted as integers. Useful
  to accelerate the search of a determinant

`psi_det <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ integer(bit_kind), psi_det, (N_int,2,psi_det_size) ]/;">`_
  The wave function determinants. Initialized with Hartree-Fock if the EZFIO file
  is empty

`psi_det_size <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ integer, psi_det_size ]/;">`_
  Size of the psi_det/psi_coef arrays

`psi_det_sorted <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ integer(bit_kind), psi_det_sorted, (N_int,2,N_det) ]/;">`_
  Wave function sorted by determinants contribution to the norm (state-averaged)

`psi_det_sorted_bit <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/BEGIN_PROVIDER [ integer(bit_kind), psi_det_sorted_bit, (N_int,2,N_det) ]/;">`_
  Determinants on which we apply <i|H|psi> for perturbation.
  o They are sorted by determinants interpreted as integers. Useful
  to accelerate the search of a determinant

`read_dets <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/subroutine read_dets(det,Nint,Ndet)/;">`_
  Reads the determinants from the EZFIO file

`save_wavefunction <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants.irp.f#L/subroutine save_wavefunction/;">`_
  Save the wave function into the EZFIO file

`double_exc_bitmask <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants_bitmasks.irp.f#L/BEGIN_PROVIDER [ integer(bit_kind), double_exc_bitmask, (N_int, 4, N_double_exc_bitmasks) ]/;">`_
  double_exc_bitmask(:,1,i) is the bitmask for holes of excitation 1
  double_exc_bitmask(:,2,i) is the bitmask for particles of excitation 1
  double_exc_bitmask(:,3,i) is the bitmask for holes of excitation 2
  double_exc_bitmask(:,4,i) is the bitmask for particles of excitation 2
  for a given couple of hole/particle excitations i.

`n_double_exc_bitmasks <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants_bitmasks.irp.f#L/BEGIN_PROVIDER [ integer, N_double_exc_bitmasks ]/;">`_
  Number of double excitation bitmasks

`n_single_exc_bitmasks <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants_bitmasks.irp.f#L/BEGIN_PROVIDER [ integer, N_single_exc_bitmasks ]/;">`_
  Number of single excitation bitmasks

`single_exc_bitmask <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/determinants_bitmasks.irp.f#L/BEGIN_PROVIDER [ integer(bit_kind), single_exc_bitmask, (N_int, 2, N_single_exc_bitmasks) ]/;">`_
  single_exc_bitmask(:,1,i) is the bitmask for holes
  single_exc_bitmask(:,2,i) is the bitmask for particles
  for a given couple of hole/particle excitations i.

`ci_eigenvectors <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI.irp.f#L/&BEGIN_PROVIDER [ double precision, CI_eigenvectors, (N_det,N_states) ]/;">`_
  Eigenvectors/values of the CI matrix

`ci_electronic_energy <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI.irp.f#L/BEGIN_PROVIDER [ double precision, CI_electronic_energy, (N_states) ]/;">`_
  Eigenvectors/values of the CI matrix

`ci_energy <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI.irp.f#L/BEGIN_PROVIDER [ double precision, CI_energy, (N_states) ]/;">`_
  N_states lowest eigenvalues of the CI matrix

`diag_algorithm <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI.irp.f#L/BEGIN_PROVIDER [ character*(64), diag_algorithm ]/;">`_
  Diagonalization algorithm (Davidson or Lapack)

`diagonalize_ci <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI.irp.f#L/subroutine diagonalize_CI/;">`_
  Replace the coefficients of the CI states by the coefficients of the
  eigenstates of the CI matrix

`ci_sc2_eigenvectors <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI_SC2.irp.f#L/&BEGIN_PROVIDER [ double precision, CI_SC2_eigenvectors, (N_det,N_states) ]/;">`_
  Eigenvectors/values of the CI matrix

`ci_sc2_electronic_energy <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI_SC2.irp.f#L/BEGIN_PROVIDER [ double precision, CI_SC2_electronic_energy, (N_states) ]/;">`_
  Eigenvectors/values of the CI matrix

`ci_sc2_energy <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI_SC2.irp.f#L/BEGIN_PROVIDER [ double precision, CI_SC2_energy, (N_states) ]/;">`_
  N_states lowest eigenvalues of the CI matrix

`diagonalize_ci_sc2 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/diagonalize_CI_SC2.irp.f#L/subroutine diagonalize_CI_SC2/;">`_
  Replace the coefficients of the CI states by the coefficients of the
  eigenstates of the CI matrix

`filter_connected <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/filter_connected.irp.f#L/subroutine filter_connected(key1,key2,Nint,sze,idx)/;">`_
  Filters out the determinants that are not connected by H
  .br
  returns the array idx which contains the index of the
  .br
  determinants in the array key1 that interact
  .br
  via the H operator with key2.
  .br
  idx(0) is the number of determinants that interact with key1

`filter_connected_davidson <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/filter_connected.irp.f#L/subroutine filter_connected_davidson(key1,key2,Nint,sze,idx)/;">`_
  Filters out the determinants that are not connected by H
  .br
  returns the array idx which contains the index of the
  .br
  determinants in the array key1 that interact
  .br
  via the H operator with key2.
  .br
  idx(0) is the number of determinants that interact with key1

`filter_connected_i_h_psi0 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/filter_connected.irp.f#L/subroutine filter_connected_i_H_psi0(key1,key2,Nint,sze,idx)/;">`_
  returns the array idx which contains the index of the
  .br
  determinants in the array key1 that interact
  .br
  via the H operator with key2.
  .br
  idx(0) is the number of determinants that interact with key1

`filter_connected_i_h_psi0_sc2 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/filter_connected.irp.f#L/subroutine filter_connected_i_H_psi0_SC2(key1,key2,Nint,sze,idx,idx_repeat)/;">`_
  standard filter_connected_i_H_psi but returns in addition
  .br
  the array of the index of the non connected determinants to key1
  .br
  in order to know what double excitation can be repeated on key1
  .br
  idx_repeat(0) is the number of determinants that can be used
  .br
  to repeat the excitations

`get_s2 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/s2.irp.f#L/subroutine get_s2(key_i,key_j,phase,Nint)/;">`_
  Returns <S^2>

`get_s2_u0 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/s2.irp.f#L/subroutine get_s2_u0(psi_keys_tmp,psi_coefs_tmp,n,nmax,s2)/;">`_
  Undocumented

`s_z <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/s2.irp.f#L/BEGIN_PROVIDER [ double precision, S_z ]/;">`_
  Undocumented

`s_z2_sz <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/s2.irp.f#L/&BEGIN_PROVIDER [ double precision, S_z2_Sz ]/;">`_
  Undocumented

`a_operator <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine a_operator(iorb,ispin,key,hjj,Nint,na,nb)/;">`_
  Needed for diag_H_mat_elem

`ac_operator <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine ac_operator(iorb,ispin,key,hjj,Nint,na,nb)/;">`_
  Needed for diag_H_mat_elem

`decode_exc <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine decode_exc(exc,degree,h1,p1,h2,p2,s1,s2)/;">`_
  Decodes the exc arrays returned by get_excitation.
  h1,h2 : Holes
  p1,p2 : Particles
  s1,s2 : Spins (1:alpha, 2:beta)
  degree : Degree of excitation

`det_connections <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/BEGIN_PROVIDER [ integer*8, det_connections, (N_con_int,N_det) ]/;">`_
  .br

`diag_h_mat_elem <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/double precision function diag_H_mat_elem(det_in,Nint)/;">`_
  Computes <i|H|i>

`get_double_excitation <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine get_double_excitation(det1,det2,exc,phase,Nint)/;">`_
  Returns the two excitation operators between two doubly excited determinants and the phase

`get_excitation <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine get_excitation(det1,det2,exc,degree,phase,Nint)/;">`_
  Returns the excitation operators between two determinants and the phase

`get_excitation_degree <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine get_excitation_degree(key1,key2,degree,Nint)/;">`_
  Returns the excitation degree between two determinants

`get_excitation_degree_vector <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine get_excitation_degree_vector(key1,key2,degree,Nint,sze,idx)/;">`_
  Applies get_excitation_degree to an array of determinants

`get_mono_excitation <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine get_mono_excitation(det1,det2,exc,phase,Nint)/;">`_
  Returns the excitation operator between two singly excited determinants and the phase

`get_occ_from_key <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine get_occ_from_key(key,occ,Nint)/;">`_
  Returns a list of occupation numbers from a bitstring

`h_u_0 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine H_u_0(v_0,u_0,H_jj,n,keys_tmp,Nint)/;">`_
  Computes v_0 = H|u_0>
  .br
  n : number of determinants
  .br
  H_jj : array of <j|H|j>

`i_h_j <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine i_H_j(key_i,key_j,Nint,hij)/;">`_
  Returns <i|H|j> where i and j are determinants

`i_h_psi <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine i_H_psi(key,keys,coef,Nint,Ndet,Ndet_max,Nstate,i_H_psi_array)/;">`_
  <key|H|psi> for the various Nstates

`i_h_psi_sc2 <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/subroutine i_H_psi_SC2(key,keys,coef,Nint,Ndet,Ndet_max,Nstate,i_H_psi_array,idx_repeat)/;">`_
  <key|H|psi> for the various Nstate
  .br
  returns in addition
  .br
  the array of the index of the non connected determinants to key1
  .br
  in order to know what double excitation can be repeated on key1
  .br
  idx_repeat(0) is the number of determinants that can be used
  .br
  to repeat the excitations

`n_con_int <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/slater_rules.irp.f#L/BEGIN_PROVIDER [ integer, N_con_int ]/;">`_
  Number of integers to represent the connections between determinants

`h_matrix_all_dets <http://github.com/LCPQ/quantum_package/tree/master/src/Dets/utils.irp.f#L/BEGIN_PROVIDER [ double precision, H_matrix_all_dets,(N_det,N_det) ]/;">`_
  H matrix on the basis of the slater deter;inants defined by psi_det