Molecular Dynamic

This code can be used for the study of classical gases with weak interaction (Van der Waals). The evolution of the system is done by the Speed Verlet algorithm.

Compilation

The compilation of the codes is very simple, we simply use:

gcc input.c -o output.out -lm
./output.out

Pipe in gnuplot

In linux you can call gnuplot from your c code as follows:

FILE *pipe = popen("gnuplot", "w");
assert(pipe);
/*
Development code of our program
*/
pclose(pipe);

This form of call can be used in a window, provided that the compilation of the code is done through a console (gnuplot and gcc must be environment variables).

/*
Print that allows to visualize the evolution of the system.
Keyword Arguments:
sys: class_system * (particle system).
gnuplot: ----> environment variable (Window).
         ----> object FILE * (Linux).
*/
void printer_system(class_system *sys, FILE *gnuplot){
    int i;
   
    fprintf(gnuplot, "set title '{/=20 Gas Model, pass %d}'\n", sys->accountant);
    fprintf(gnuplot, "set xlabel  '{/=15 X}'\n");  
    fprintf(gnuplot, "set zlabel  '{/=15 Z}'\n");
    fprintf(gnuplot, "set ylabel  '{/=15 Y}'\n");
    fprintf(gnuplot, "splot '-' with p pointtype 6 t ''\n");
  
    for(i = 0; i < N; i++)
        fprintf(gnuplot, "%lf\t%lf\t%lf\n", sys -> position[i][0], 
                                    sys -> position[i][1], sys ->position[i][2]);
    
    fprintf(gnuplot, "e\n");
    fflush(gnuplot);
}