Gromacs  2016.5
calculate-ewald-splitting-coefficient.h File Reference
`#include "gromacs/utility/real.h"` Include dependency graph for calculate-ewald-splitting-coefficient.h:

## Description

Declares functions for computing Ewald splitting coefficients.

These belong in the maths module because they do simple maths and are used many parts of Gromacs.

## 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.