reformatting and use citeme class

#include "fix_rhok.h"

#include "error.h"

#include "citeme.h"

#include "update.h"

#include "respa.h"

#include "atom.h"

using namespace LAMMPS_NS;

using namespace FixConst;

// Constructor: all the parameters to this fix specified in

// the LAMMPS input get passed in

static const char cite_flow_gauss[] =

  "Bias on the collective density field (fix rhok):\n\n"

  "@Article{pedersen_jcp139_104102_2013,\n"

  "title = {Direct calculation of the solid-liquid Gibbs free energy difference in a single equilibrium simulation},\n"

  "volume = {139},\n"

  "number = {10},\n"

  "url = {http://aip.scitation.org/doi/10.1063/1.4818747},\n"

  "doi = {10.1063/1.4818747},\n"

  "urldate = {2017-10-03},\n"

  "journal = {J. Chem. Phys.},\n"

  "author = {Pedersen, Ulf R.},\n"

  "year = {2013},\n"

  "pages = {104102}\n"

  "}\n\n";

FixRhok::FixRhok( LAMMPS* inLMP, int inArgc, char** inArgv )

  : Fix( inLMP, inArgc, inArgv )

{

  if (lmp->citeme) lmp->citeme->add(cite_flow_gauss);

  // Check arguments

  if( inArgc != 8 ) 

  error->all(FLERR,"Illegal fix rhoKUmbrella command" );

  return mask;

}

/*int FixRhok::setmask()

{

  int mask = 0;

  mask |= POST_FORCE;

  mask |= POST_FORCE_RESPA;

  mask |= MIN_POST_FORCE;

  return mask;

}*/

// Initializes the fix at the beginning of a run

void

FixRhok::init()