DistinctDoubleType_t

type, public, extends(EnumBase_t) :: DistinctDoubleType_t

This represents a distinct double excitation (compare Table 4.3 of [@DobrautzThesis2019]) A distinct double excitation consists of the two double excitations $e_{ij,kl}$ which are connected by exchange $e_{il,kj}$ .

Because of $e_{ij,kl} = e_{kl,ij}$ we can order such that $i \leq k$ . The matrix element requires $e_{ij,kl}$ and $e_{il,kj}$ . For the notation of distinct double excitation we will order such that $j \leq l$ . In the following we assume $i < j < k < l$ .

Example: The distinct type iijk consists of $e_{ii,jk}$ and $e_{ik,ji}$ . The first is a non-overlap double excitation with a single Weight on i and a single raising excitation from k to j; the latter is a fullstart_L_to_R i.e. $\underline{RL}(i) R\overline{L}(j) \overline{R}(k)$

Components

Type	Visibility		Name		Initial
integer,	public	::	val
type(ExcitationType_t),	public	::	repr			The two subtypes usually do not differ. If the two subtypes differ, then it is always a pairing with `non_overlap`. For this reason we can choose one representative. For example: `kikj` and `kjki` are both `fullstop_lowering`. `ijkl` is `non_overlap`, the corresponding exchanged excitation `ilkj` is `double_R_to_L_to_R`, hence we choose `double_R_to_L_to_R` as representation. Note Older code does not clearly distinguish between `DistinctDoubleExcitation_t` and `ExcitationType_t`, so the `repr` is particularly useful here.
type(ExcitationType_t),	public	::	other			The other Excitation that is not the representative
character(len=2),	public	::	label			The label in Table 4.3 of [@DobrautzThesis2019]
integer,	public	::	idx_for_repr(4)	=	[1, 2, 3, 4]	Store the permutation for outputting the representation index If we have for example the `DistinctDoubleType_t` `jilk`, then the index of the representation shall refer to the `double_L_to_R_to_L` excitation and be `jkli` instead of the `non_overlap` part which would be `jilk`. The swap is only relevant for distinct doubles with a non-overlap excitation. Hence we default-initialize to the identity permutation.

Constructor

public interface DistinctDoubleType_t

private elemental function construct_DistinctDoubleType_t_ijkl(idx) result(res)

Arguments

Type	Intent	Optional	Attributes		Name
type(ijkl_Index_t),	intent(in)			::	idx

Return Value type(DistinctDoubleType_t)

private elemental function construct_DistinctDoubleType_t_ijab(idx) result(res)

Arguments

Type	Intent	Optional	Attributes		Name
type(ijab_Index_t),	intent(in)			::	idx

Return Value type(DistinctDoubleType_t)

Type-Bound Procedures

generic, public :: operator(==) => eq_EnumBase_t

private elemental function eq_EnumBase_t(this, other)

Arguments

Type	Intent	Optional	Attributes		Name
class(EnumBase_t),	intent(in)			::	this
class(EnumBase_t),	intent(in)			::	other

Return Value logical

generic, public :: operator(/=) => neq_EnumBase_t

private elemental function neq_EnumBase_t(this, other)

Arguments

Type	Intent	Optional	Attributes		Name
class(EnumBase_t),	intent(in)			::	this
class(EnumBase_t),	intent(in)			::	other

DistinctDoubleType_t Derived Type

Contents

Variables

Constructor

Type-Bound Procedures

type, public, extends(EnumBase_t) :: DistinctDoubleType_t

Components

Constructor

public interface DistinctDoubleType_t

private elemental function construct_DistinctDoubleType_t_ijkl(idx) result(res)

Arguments

Return Value type(DistinctDoubleType_t)

private elemental function construct_DistinctDoubleType_t_ijab(idx) result(res)

Arguments

Return Value type(DistinctDoubleType_t)

Type-Bound Procedures

generic, public :: operator(==) => eq_EnumBase_t

private elemental function eq_EnumBase_t(this, other)

Arguments

Return Value logical

generic, public :: operator(/=) => neq_EnumBase_t

private elemental function neq_EnumBase_t(this, other)

Arguments

Return Value logical