tblite_coulomb_ewald Module Reference

Helper tools for dealing with Ewald summation related calculations. More...

Data Types
type	ewald_cache
	Cell-dependent reciprocal coefficients, shared by energies and derivatives. These do not depend on coordinates or on the work partition. More...
interface	get_value
	Interaction at specified distance. More...

Functions/Subroutines
subroutine	update_ewald_cache (self, lattice, alpha, tolerance, ko)
	Rebuild only when the cell, splitting parameter, tolerance or kernel changes.
subroutine, public	get_alpha (lattice, alpha, multipole)
	Convenience interface to determine Ewald splitting parameter.
real(wp) function, public	get_rec_cutoff (alpha, volume, conv)
	Return cutoff for reciprocal contributions.
real(wp) function, public	get_dir_cutoff (alpha, conv)
	Return cutoff for real-space contributions.

Variables
real(wp), parameter	euler_gamma = 0.57721566490153286061_wp

Detailed Description

Helper tools for dealing with Ewald summation related calculations.

Function/Subroutine Documentation

get_alpha()

subroutine, public tblite_coulomb_ewald::get_alpha	(	real(wp), dimension(:, :), intent(in)	lattice,
		real(wp), intent(out)	alpha,
		logical, intent(in)	multipole )

Convenience interface to determine Ewald splitting parameter.

Parameters

[in]	lattice	Lattice vectors
[out]	alpha	Estimated Ewald splitting parameter
[in]	multipole	Multipole expansion is used

get_dir_cutoff()

real(wp) function, public tblite_coulomb_ewald::get_dir_cutoff	(	real(wp), intent(in)	alpha,
		real(wp), intent(in)	conv )

Return cutoff for real-space contributions.

Parameters

[in]	alpha	Parameter of Ewald summation
[in]	conv	Tolerance for Ewald summation

Returns

Magnitude of real-space vector

get_rec_cutoff()

real(wp) function, public tblite_coulomb_ewald::get_rec_cutoff	(	real(wp), intent(in)	alpha,
		real(wp), intent(in)	volume,
		real(wp), intent(in)	conv )

Return cutoff for reciprocal contributions.

Parameters

[in]	alpha	Parameter of Ewald summation
[in]	volume	Volume of the unit cell
[in]	conv	Tolerance value

Returns

Magnitude of reciprocal vector

update_ewald_cache()

subroutine tblite_coulomb_ewald::update_ewald_cache	(	class(ewald_cache), intent(inout)	self,
		real(wp), dimension(3, 3), intent(in)	lattice,
		real(wp), intent(in)	alpha,
		real(wp), intent(in)	tolerance,
		logical, intent(in), optional	ko )

Rebuild only when the cell, splitting parameter, tolerance or kernel changes.

Parameters

[in,out]	self	Cached reciprocal-space coefficients
[in]	lattice	Real-space lattice vectors
[in]	alpha	Ewald splitting parameter
[in]	tolerance	Convergence tolerance for selecting reciprocal vectors
[in]	ko	Include the Klopman-Ohno 1/r^3 coefficients; absent selects only 1/r