ewald_utils.h File Reference

#include "gromacs/math/vec.h"
#include "gromacs/math/vectypes.h"
#include "gromacs/mdtypes/inputrec.h"
#include "gromacs/pbcutil/pbc.h"
#include "gromacs/utility/gmxassert.h"
#include "gromacs/utility/real.h"

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Description

Declares utility functions related to Ewald.

Author

Mark Abraham mark..nosp@m.j.ab.nosp@m.raham.nosp@m.@gma.nosp@m.il.co.nosp@m.m

Szilárd Páll pall..nosp@m.szil.nosp@m.ard@g.nosp@m.mail.nosp@m..com

Classes
class	EwaldBoxZScaler
	Class to handle box scaling for Ewald and PME. More...

Functions
real	calc_ewaldcoeff_q (real rc, real rtol)
	Computes the Ewald splitting coefficient for Coulomb. More...
real	calc_ewaldcoeff_lj (real rc, real rtol)
	Computes the Ewald splitting coefficient for LJ. More...

Function Documentation

real calc_ewaldcoeff_lj	(	real	rc,
		real	rtol
	)

Computes the Ewald splitting coefficient for LJ.

Returns a value of beta that satisfies dtol > erfc(beta * rc) * (1

• beta^2 * rc^2 + 0.5 * beta^4 * rc^4) (and is very close to equality), which is used in LJ-PME.

Parameters

[in]	rc	Cutoff radius
[in]	rtol	Required maximum value of the short-ranged potential at the cutoff (ie. ewald-rtol-lj)

Returns

The value of the splitting coefficient that produces the required dtol at rc.

real calc_ewaldcoeff_q	(	real	rc,
		real	rtol
	)

Computes the Ewald splitting coefficient for Coulomb.

Returns a value of beta that satisfies rtol > erfc(beta * rc) (and is very close to equality). That value is used the same way in all Coulomb-based Ewald methods.

Parameters

[in]	rc	Cutoff radius
[in]	rtol	Required maximum value of the short-ranged potential at the cutoff (ie. ewald-rtol)

Returns

The value of the splitting coefficient that produces the required dtol at rc.