X-Git-Url: https://hackdaworld.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=moldyn.c;h=3d669d223401ddd8fe9277e9ea07654186e7018e;hb=83775c491117faa149281d0302fc8b8064d6b080;hp=57ae62f75c69ffce130d8cae8af6e5ead6588965;hpb=4e6604346459a4a8619bfc45f2a4b7dbd925ae86;p=physik%2Fposic.git

diff --git a/moldyn.c b/moldyn.c
index 57ae62f..3d669d2 100644
--- a/moldyn.c
+++ b/moldyn.c
@@ -14,6 +14,7 @@
 #include "math/math.h"
 #include "init/init.h"
 #include "random/random.h"
+#include "visual/visual.h"
 
 
 int create_lattice(unsigned char type,int element,double mass,double lc,
@@ -177,6 +178,77 @@ t_3dvec get_total_p(t_atom *atom, int count) {
 }
 
 
+/*
+ *
+ * 'integration of newtons equation' - algorithms
+ *
+ */
+
+/* start the integration */
+
+int moldyn_integrate(t_moldyn *moldyn) {
+
+	int i;
+
+	/* calculate initial forces */
+	moldyn->force(moldyn);
+
+	for(i=0;i<moldyn->time_steps;i++) {
+		/* integration step */
+		moldyn->integrate(moldyn);
+
+		/* check for visualiziation */
+		// to be continued ...
+		if(!(i%1)) {
+			visual_atoms(moldyn->visual,i*moldyn->tau,
+			             moldyn->atom,moldyn->count);
+		}
+	}
+
+	return 0;
+}
+
+/* velocity verlet */
+
+int velocity_verlet(t_moldyn *moldyn) {
+
+	int i,count;
+	double tau,tau_square;
+	t_3dvec delta;
+	t_atom *atom;
+
+	atom=moldyn->atom;
+	count=moldyn->count;
+	tau=moldyn->tau;
+
+	tau_square=tau*tau;
+
+	for(i=0;i<count;i++) {
+		/* new positions */
+		v3_scale(&delta,&(atom[i].v),tau);
+		v3_add(&(atom[i].r),&(atom[i].r),&delta);
+		v3_scale(&delta,&(atom[i].f),0.5*tau_square/atom[i].mass);
+		v3_add(&(atom[i].r),&(atom[i].r),&delta);
+		v3_per_bound(&(atom[i].r),&(moldyn->dim));
+
+		/* velocities */
+		v3_scale(&delta,&(atom[i].f),0.5*tau/atom[i].mass);
+		v3_add(&(atom[i].r),&(atom[i].r),&delta);
+	}
+
+	/* forces depending on chosen potential */
+	moldyn->force(moldyn);
+
+	for(i=0;i<count;i++) {
+		/* again velocities */
+		v3_scale(&delta,&(atom[i].f),0.5*tau/atom[i].mass);
+		v3_add(&(atom[i].v),&(atom[i].v),&delta);
+	}
+
+	return 0;
+}
+
+
 /*
  *
  * potentials & corresponding forces
@@ -250,7 +322,7 @@ int force_lennard_jones(t_moldyn *moldyn) {
 				h1*=h2;				/* 1/r^14 */
 				h1*=sig12;
 				h2*=sig6;
-				d=-12.0*h1+6.0*h2;
+				d=12.0*h1-6.0*h2;
 				d*=eps;
 				v3_scale(&force,&distance,d);
 				v3_add(&(atom[j].f),&(atom[j].f),&force);