src/gromacs/applied_forces/electricfield.h

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  35 /*! \libinternal \file
  36  * \brief
  37  * Declares module creation function for applied electric fields
  38  *
  39  * \author David van der Spoel <david.vanderspoel@icm.uu.se>
  40  * \ingroup module_applied_forces
  41  * \inlibraryapi
  42  */
  43 #ifndef GMX_APPLIED_FORCES_ELECTRICFIELD_H
  44 #define GMX_APPLIED_FORCES_ELECTRICFIELD_H
  45
  46 #include <memory>
  47
  48 namespace gmx
  49 {
  50
  51 class IMDModule;
  52
  53 /*! \brief
  54  * Creates a module for an external electric field.
  55  *
  56  * The returned class describes the time dependent electric field that can
  57  * be applied to all charges in a simulation. The field is described
  58  * by the following:
  59  *     E(t) = A cos(omega*(t-t0))*exp(-sqr(t-t0)/(2.0*sqr(sigma)));
  60  * If sigma = 0 there is no pulse and we have instead
  61  *     E(t) = A cos(omega*t)
  62  *
  63  * force is kJ mol^-1 nm^-1 = e * kJ mol^-1 nm^-1 / e
  64  *
  65  * WARNING:
  66  * There can be problems with the virial.
  67  * Since the field is not self-consistent this is unavoidable.
  68  * For neutral molecules the virial is correct within this approximation.
  69  * For neutral systems with many charged molecules the error is small.
  70  * But for systems with a net charge or a few charged molecules
  71  * the error can be significant when the field is high.
  72  * Solution: implement a self-consistent electric field into PME.
  73  */
  74 std::unique_ptr<IMDModule> createElectricFieldModule();
  75
  76 } // namespace gmx
  77
  78 #endif