gasci_pchb_doubles_spinorb_fullyweighted Module

precomputed heat bath implementation for GASCI using spin orbitals and full weighting


Uses


Contents

Derived Types

Functions

Subroutines


Derived Types

type, public, extends(DoubleExcitationGenerator_t) ::  GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t

The GAS PCHB excitation generator for doubles using spin orbitals and doing full weighting. This means that first a hole is chosen via ( p( A | I J) |{A \notin D_i} ) !! then a second hole is chosen via ( p( B | I J A) | ).

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Components

Type Visibility Attributes Name Initial
logical, public :: use_lookup = .false.

Use a lookup for the supergroup index in global_det_data
logical, public :: create_lookup = .false.

Create and manage! the supergroup index lookup in global_det_data.
class(ParticleSelector_t), private, allocatable :: particle_selector

The particle selector for I, J
type(AliasSampler_2D_t), private :: A_sampler

The sampler for the first hole A. It yields where IJ is a fused index I < J and i_sg is the supergroup.
type(AliasSampler_3D_t), private :: B_sampler

The sampler for the second hole B. It yields where IJ is a fused index I < J, A is the first hole and i_sg is the supergroup.
class(GASSpec_t), private, allocatable :: GAS_spec
type(SuperGroupIndexer_t), private, pointer :: indexer => null()
integer(kind=n_int), private :: last_possible_occupied

The last element of the ilut array has some elements which are not used, if the number of spinorbitals is not a multiple of bitsize_n_int. To correctly zero them this bitmask is 1 wherever a determinant could be occupied in the last element, and 0 otherwise.

Type-Bound Procedures

procedure , public :: init => GAS_doubles_PCHB_init Subroutine
procedure , public :: finalize => GAS_doubles_PCHB_finalize Subroutine
procedure , public :: gen_exc => GAS_doubles_PCHB_gen_exc Subroutine
procedure , public :: get_pgen => GAS_doubles_PCHB_get_pgen Function
procedure , public :: gen_all_excits => GAS_doubles_PCHB_gen_all_excits Subroutine
procedure , private , :: compute_samplers => GAS_doubles_PCHB_compute_samplers Subroutine
procedure , private , :: get_unoccupied Subroutine

Functions

private function GAS_doubles_PCHB_get_pgen(this, nI, ilutI, ex, ic, ClassCount2, ClassCountUnocc2) result(pgen)

@brief Calculate the probability of drawing a given double excitation ex

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Arguments

Type IntentOptional Attributes Name
class(GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t), intent(inout) :: this
integer, intent(in) :: nI(nel)
integer(kind=n_int), intent(in) :: ilutI(0:NIfTot)
integer, intent(in) :: ex(2,maxExcit)
integer, intent(in) :: ic
integer, intent(in) :: ClassCount2(ScratchSize)
integer, intent(in) :: ClassCountUnocc2(ScratchSize)

Return Value real(kind=dp)


Subroutines

private subroutine GAS_doubles_PCHB_init(this, GAS_spec, use_lookup, create_lookup, PCHB_particle_selection)

@brief Initialize the pchb excitation generator

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Arguments

Type IntentOptional Attributes Name
class(GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t), intent(inout) :: this
class(GASSpec_t), intent(in) :: GAS_spec
logical, intent(in) :: use_lookup
logical, intent(in) :: create_lookup
type(PCHB_ParticleSelection_t), intent(in) :: PCHB_particle_selection

private subroutine GAS_doubles_PCHB_finalize(this)

Finalize everything

Arguments

Type IntentOptional Attributes Name
class(GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t), intent(inout) :: this

private subroutine GAS_doubles_PCHB_gen_exc(this, nI, ilutI, nJ, ilutJ, exFlag, ic, ex, tParity, pGen, hel, store, part_type)

Given the initial determinant (both as nI and ilut), create a random double excitation using the hamiltonian matrix elements as weights

Arguments

Type IntentOptional Attributes Name
class(GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t), intent(inout) :: this
integer, intent(in) :: nI(nel)
integer(kind=n_int), intent(in) :: ilutI(0:NIfTot)
integer, intent(out) :: nJ(nel)
integer(kind=n_int), intent(out) :: ilutJ(0:NifTot)
integer, intent(in) :: exFlag
integer, intent(out) :: ic
integer, intent(out) :: ex(2,maxExcit)
logical, intent(out) :: tParity
real(kind=dp), intent(out) :: pGen
real(kind=dp), intent(out) :: hel
type(excit_gen_store_type), intent(inout), target :: store
integer, intent(in), optional :: part_type

private subroutine GAS_doubles_PCHB_compute_samplers(this, PCHB_particle_selection)

computes and stores values for the alias sampling table n_supergroup * number_of_fused_indices * 3 * (bytes_per_sampler)

Arguments

Type IntentOptional Attributes Name
class(GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t), intent(inout) :: this
type(PCHB_ParticleSelection_t), intent(in) :: PCHB_particle_selection

private subroutine GAS_doubles_PCHB_gen_all_excits(this, nI, n_excits, det_list)

Arguments

Type IntentOptional Attributes Name
class(GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t), intent(in) :: this
integer, intent(in) :: nI(nEl)
integer, intent(out) :: n_excits
integer(kind=n_int), intent(out), allocatable :: det_list(:,:)

private pure subroutine get_unoccupied(this, ilutI, ilut_unoccupied, unoccupied)

Return a bitmask and enumeration of the unoccupied spin orbitals.

Arguments

Type IntentOptional Attributes Name
class(GAS_PCHB_DoublesSpinorbFullyWeightedExcGenerator_t), intent(in) :: this
integer(kind=n_int), intent(in) :: ilutI(0:nIfD)
integer(kind=n_int), intent(out) :: ilut_unoccupied(0:nIfD)
integer, intent(out) :: unoccupied(nBasis-nEl)