EvalVacf.c

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/*
 * This file is part of Lamina.
 *
 * Lamina is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Lamina is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Lamina. If not, see <https://www.gnu.org/licenses/>.
 
 Copyright (C) 2025 Harish Charan, University of Durham, UK
 
 */
 
 
#include<stdio.h>
#include"global.h"
 
void AccumVacf();
void EvalVacf(){
  int n, nb, ni;
  double viscVec = 0.;
  double v[3];
  for(n = 1 ; n <= nAtom ; n ++){
    v[1] = vx[n] - 0.5*ax[n]*deltaT;
    v[2] = vy[n] - 0.5*ay[n]*deltaT;
    viscVec += v[1]*v[2];
  }
  viscVec += rfAtom;
  for(nb = 1 ; nb <= nBuffAcf ; nb ++){
    indexAcf[nb] ++;
    if(indexAcf[nb] <= 0)continue;
    if(indexAcf[nb] == 1){
      viscAcfOrg[nb] = viscVec;
    }
    ni = indexAcf[nb];
    viscAcf[nb][ni] = viscAcfOrg[nb]*viscVec;
  }
  AccumVacf();
}