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110 lines
2.7 KiB
ReStructuredText
110 lines
2.7 KiB
ReStructuredText
.. _perturbation:
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.. program:: perturbation
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.. default-role:: option
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============
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Perturbation
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============
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All subroutines in ``*.irp.f`` starting with `pt2_` in the current directory are
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perturbation computed using the routine `i_H_psi`. Other cases are not allowed.
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The arguments of the `pt2_` are always:
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.. code-block:: fortran
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subroutine pt2_...( &
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psi_ref, &
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psi_ref_coefs, &
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E_refs, &
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det_pert, &
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c_pert, &
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e_2_pert, &
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H_pert_diag, &
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Nint, &
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Ndet, &
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N_st )
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integer , intent(in) :: Nint,Ndet,N_st
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integer(bit_kind), intent(in) :: psi_ref(Nint,2,Ndet)
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double precision , intent(in) :: psi_ref_coefs(Ndet,N_st)
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double precision , intent(in) :: E_refs(N_st)
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integer(bit_kind), intent(in) :: det_pert(Nint,2)
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double precision , intent(out) :: c_pert(N_st),e_2_pert(N_st),H_pert_diag
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`psi_ref`
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bitstring of the determinants present in the various `N_st` states
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`psi_ref_coefs`
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coefficients of the determinants on the various `N_st` states
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`E_refs`
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Energy of the various `N_st` states
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`det_pert`
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Perturber determinant
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`c_pert`
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Perturbative coefficients for the various states
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`e_2_pert`
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Perturbative energetic contribution for the various states
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`H_pert_diag`
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Diagonal |H| matrix element of the perturber
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`Nint`
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Should be equal to `N_int`
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`Ndet`
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Number of determinants `i` in |Psi| on which we apply <det_pert | |H| | `i`>
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`N_st`
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Number of states
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EZFIO parameters
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----------------
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.. option:: do_pt2
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If `True`, compute the |PT2| contribution
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Default: True
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.. option:: PT2_max
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The selection process stops when the largest |PT2| (for all the state) is lower
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than `pt2_max` in absolute value
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Default: 0.0001
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.. option:: PT2_relative_error
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Stop stochastic |PT2| when the relative error is smaller than `PT2_relative_error`
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Default: 0.005
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.. option:: correlation_energy_ratio_max
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The selection process stops at a fixed correlation ratio (useful for getting same accuracy between molecules).
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Defined as :math:`{E_{CI}-E_{HF}}/{E_{CI}+E_{PT2} - E_{HF}}`.
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Default: 1.00
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.. option:: h0_type
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Type of zeroth-order Hamiltonian [ EN | Barycentric | Variance | SOP ]
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Default: EN
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