cell_opt_utils Module Reference

Parse CELL_OPT constraints, build symmetry constraint rows, and compute the cell enthalpy gradient. More...

Functions/Subroutines
subroutine, public	read_external_press_tensor (geo_section, cell, pres_ext, mtrx, input_to_opt)
	Reads the external pressure tensor.
subroutine, public	parse_cell_constraint (constraint_tokens, cell, explicit, mask)
	Parses the tokens of the CONSTRAINT keyword into a cell component mask.
pure character(len=default_string_length) function, public	cell_opt_constraint_label (mask)
	Returns the label of the cell constraint mask.
subroutine, public	symmetry_constraint_rows (symmetry_id, mask, lin_w, n_lin_rows, eq_pair, n_eq_rows)
	Translate a crystal system into cell constraint rows.
integer function, public	spgr_point_group_symmetry_id (spgr, cell)
	Identify the canonical crystal system preserved by a space group's point group.
pure subroutine, public	parse_token (token, accepted, token_mask, reject_reason)
	Classify one CONSTRAINT token without aborting (decision half of the parser).
subroutine, public	get_dg_dh (gradient, av_ptens, pres_ext, cell, mtrx, pres_int)
	Computes the derivatives for the cell.

Detailed Description

Parse CELL_OPT constraints, build symmetry constraint rows, and compute the cell enthalpy gradient.

History

03.2008 - Teodoro Laino [tlaino] - University of Zurich - Cell Optimization

Function/Subroutine Documentation

read_external_press_tensor()

subroutine, public cell_opt_utils::read_external_press_tensor	(	type(section_vals_type), pointer	geo_section,
		type(cell_type), pointer	cell,
		real(kind=dp), intent(out)	pres_ext,
		real(kind=dp), dimension(3, 3), intent(out)	mtrx,
		real(kind=dp), dimension(3, 3), intent(in)	input_to_opt )

Reads the external pressure tensor.

Parameters

geo_section	...
cell	...
pres_ext	...
mtrx	...
input_to_opt	rotation from the input Cartesian frame to the optimization frame

Author

Teodoro Laino [tlaino] - University of Zurich - 03.2008

Definition at line 63 of file cell_opt_utils.F.

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parse_cell_constraint()

subroutine, public cell_opt_utils::parse_cell_constraint	(	character(len=*), dimension(:), intent(in)	constraint_tokens,
		type(cell_type), pointer	cell,
		logical, intent(in)	explicit,
		integer, intent(out)	mask )

Parses the tokens of the CONSTRAINT keyword into a cell component mask.

Parameters

constraint_tokens	value tokens of the CONSTRAINT keyword (char_t list)
cell	simulation cell (only the periodicity is used)
explicit	whether the CONSTRAINT keyword was given explicitly
mask	union of the fixed cell components (comp_* and mask_* bits)

Definition at line 122 of file cell_opt_utils.F.

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cell_opt_constraint_label()

pure character(len=default_string_length) function, public cell_opt_utils::cell_opt_constraint_label

(

integer, intent(in)

mask

)

Returns the label of the cell constraint mask.

Parameters

mask	bit mask of fixed cell components (comp_*, mask_*)

Returns

4-character legacy label or space-separated component names

Definition at line 209 of file cell_opt_utils.F.

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symmetry_constraint_rows()

subroutine, public cell_opt_utils::symmetry_constraint_rows	(	integer, intent(in)	symmetry_id,
		integer, intent(out)	mask,
		real(kind=dp), dimension(n_slot, n_slot), intent(out)	lin_w,
		integer, intent(out)	n_lin_rows,
		integer, dimension(2, n_geom), intent(out)	eq_pair,
		integer, intent(out)	n_eq_rows )

Translate a crystal system into cell constraint rows.

Parameters

symmetry_id	crystal system of the canonical cell
mask	comp_* bits for canonical entries fixed to zero by symmetry
lin_w	linear coupling normals, one normal per column
n_lin_rows	number of active columns in lin_w
eq_pair	index pairs [m, n] in 1..6 for geometric equalities, one pair per column
n_eq_rows	number of active columns in eq_pair

Note

Rhombohedral (a = b = c, alpha = beta = gamma) and monoclinic_gamma_ab (a = b with free gamma) produce curved geometric equalities. All other crystal systems produce constant linear rows with zero curvature.

Definition at line 257 of file cell_opt_utils.F.

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spgr_point_group_symmetry_id()

integer function, public cell_opt_utils::spgr_point_group_symmetry_id	(	type(spgr_type), intent(in), pointer	spgr,
		type(cell_type), pointer	cell )

Identify the canonical crystal system preserved by a space group's point group.

Parameters

spgr	space group with integer lattice rotations in rotations_subset
cell	symmetric start cell in the canonical frame

Returns

symmetry_id of the invariant metric form, or cell_sym_triclinic when the setting adds no canonical cell constraints

Note

Averaging the metric G = hmat^T hmat over the point group produces the invariant metric form {G : R G R^T = G for all R}. Classifying the lengths and angles of this averaged metric maps the point group to the row sets of symmetry_constraint_rows. Non-canonical settings (such as a monoclinic unique axis along a or c) return cell_sym_triclinic and add zero cell rows.

Definition at line 345 of file cell_opt_utils.F.

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parse_token()

pure subroutine, public cell_opt_utils::parse_token	(	character(len=*), intent(in)	token,
		logical, intent(out)	accepted,
		integer, intent(out)	token_mask,
		character(len=default_string_length), intent(out)	reject_reason )

Classify one CONSTRAINT token without aborting (decision half of the parser).

Parameters

token	one upper-case token of the CONSTRAINT value line
accepted	.TRUE. when the token contributes a mask
token_mask	the constraint mask contributed by an accepted token
reject_reason	empty for accepted tokens, or the abort message otherwise

Note

parse_cell_constraint applies this classification and turns a rejection into a cp_abort. Keeping the decision here keeps it unit-testable: the unit test checks the classification table without triggering aborts.

Definition at line 426 of file cell_opt_utils.F.

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get_dg_dh()

subroutine, public cell_opt_utils::get_dg_dh	(	real(kind=dp), dimension(n_slot), intent(out)	gradient,
		real(kind=dp), dimension(3, 3), intent(in)	av_ptens,
		real(kind=dp), intent(in)	pres_ext,
		type(cell_type), pointer	cell,
		real(kind=dp), dimension(3, 3), intent(in)	mtrx,
		real(kind=dp), intent(out)	pres_int )

Computes the derivatives for the cell.

Parameters

gradient	enthalpy gradient +d(E + pres_ext*V)/dq in the six canonical components
av_ptens	...
pres_ext	...
cell	...
mtrx	...
pres_int	...

Author

Teodoro Laino [tlaino] - University of Zurich - 03.2008

Definition at line 492 of file cell_opt_utils.F.

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