#include <stdio.h>
#include <stdlib.h>
+#include <math.h>
#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,
- t_3dvec *dim,t_atom **atom) {
+ int a,int b,int c,t_atom **atom) {
int count;
int ret;
t_3dvec origin;
- count=((dim->x/lc)*(dim->y/lc)*(dim->z/lc));
+ count=a*b*c;
if(type==FCC) count*=4;
if(type==DIAMOND) count*=8;
switch(type) {
case FCC:
- ret=fcc_init(dim,lc,*atom,&origin);
+ ret=fcc_init(a,b,c,lc,*atom,&origin);
break;
case DIAMOND:
- ret=diamond_init(dim,lc,*atom,&origin);
+ ret=diamond_init(a,b,c,lc,*atom,&origin);
break;
default:
- ret=-1;
printf("unknown lattice type (%02x)\n",type);
+ return -1;
}
/* debug */
printf("ok, there is something wrong ...\n");
printf("calculated -> %d atoms\n",count);
printf("created -> %d atoms\n",ret);
+ return -1;
}
while(count) {
return ret;
}
+int destroy_lattice(t_atom *atom) {
+
+ if(atom) free(atom);
+
+ return 0;
+}
+
+int thermal_init(t_atom *atom,t_random *random,int count,double t) {
+
+ /*
+ * - gaussian distribution of velocities
+ * - zero total momentum
+ * - velocity scaling (E = 3/2 N k T), E: kinetic energy
+ */
+
+ int i;
+ double v,sigma;
+ t_3dvec p_total,delta;
+
+ /* gaussian distribution of velocities */
+ v3_zero(&p_total);
+ for(i=0;i<count;i++) {
+ sigma=sqrt(2.0*K_BOLTZMANN*t/atom[i].mass);
+ /* x direction */
+ v=sigma*rand_get_gauss(random);
+ atom[i].v.x=v;
+ p_total.x+=atom[i].mass*v;
+ /* y direction */
+ v=sigma*rand_get_gauss(random);
+ atom[i].v.y=v;
+ p_total.y+=atom[i].mass*v;
+ /* z direction */
+ v=sigma*rand_get_gauss(random);
+ atom[i].v.z=v;
+ p_total.z+=atom[i].mass*v;
+ }
+
+ /* zero total momentum */
+ v3_scale(&p_total,&p_total,1.0/count);
+ for(i=0;i<count;i++) {
+ v3_scale(&delta,&p_total,1.0/atom[i].mass);
+ v3_sub(&(atom[i].v),&(atom[i].v),&delta);
+ }
+
+ /* velocity scaling */
+ scale_velocity(atom,count,t);
+
+ return 0;
+}
+
+int scale_velocity(t_atom *atom,int count,double t) {
+
+ int i;
+ double e,c;
+
+ /*
+ * - velocity scaling (E = 3/2 N k T), E: kinetic energy
+ */
+ e=0.0;
+ for(i=0;i<count;i++)
+ e+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
+ c=sqrt((2.0*e)/(3.0*count*K_BOLTZMANN*t));
+ for(i=0;i<count;i++)
+ v3_scale(&(atom[i].v),&(atom[i].v),(1.0/c));
+
+ return 0;
+}
+
+double get_e_kin(t_atom *atom,int count) {
+
+ int i;
+ double e;
+
+ e=0.0;
+
+ for(i=0;i<count;i++) {
+ e+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
+ }
+
+ return e;
+}
+
+double get_e_pot(t_moldyn *moldyn) {
+
+ return(moldyn->potential(moldyn));
+}
+
+double get_total_energy(t_moldyn *moldyn) {
+
+ double e;
+
+ e=get_e_kin(moldyn->atom,moldyn->count);
+ e+=get_e_pot(moldyn);
+
+ return e;
+}
+
+t_3dvec get_total_p(t_atom *atom, int count) {
+
+ t_3dvec p,p_total;
+ int i;
+
+ v3_zero(&p_total);
+ for(i=0;i<count;i++) {
+ v3_scale(&p,&(atom[i].v),atom[i].mass);
+ v3_add(&p_total,&p_total,&p);
+ }
+
+ return p_total;
+}
+
+double estimate_time_step(t_moldyn *moldyn,double nn_dist,double t) {
+
+ double tau;
+
+ tau=0.05*nn_dist/(sqrt(3.0*K_BOLTZMANN*t/moldyn->atom[0].mass));
+ tau*=1.0E-9;
+ if(tau<moldyn->tau)
+ printf("[moldyn] warning: time step (%f > %.15f)\n",
+ moldyn->tau,tau);
+
+ return tau;
+}
+
+
+/*
+ *
+ * 'integration of newtons equation' - algorithms
+ *
+ */
+
+/* start the integration */
+
+int moldyn_integrate(t_moldyn *moldyn) {
+
+ int i;
+ int write;
+
+ write=moldyn->write;
+
+ /* calculate initial forces */
+ moldyn->force(moldyn);
+
+ for(i=0;i<moldyn->time_steps;i++) {
+ /* integration step */
+ moldyn->integrate(moldyn);
+
+ /* check for visualiziation */
+ if(!(i%write)) {
+ 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].v),&(atom[i].v),&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
+ *
+ */
+
+/* harmonic oscillator potential and force */
+
+double potential_harmonic_oscillator(t_moldyn *moldyn) {
+
+ t_ho_params *params;
+ t_atom *atom;
+ int i,j;
+ int count;
+ t_3dvec distance;
+ double d,u;
+ double sc,equi_dist;
+
+ params=moldyn->pot_params;
+ atom=moldyn->atom;
+ sc=params->spring_constant;
+ equi_dist=params->equilibrium_distance;
+ count=moldyn->count;
+
+ u=0.0;
+ for(i=0;i<count;i++) {
+ for(j=0;j<i;j++) {
+ v3_sub(&distance,&(atom[i].r),&(atom[j].r));
+ d=v3_norm(&distance);
+ u+=(0.5*sc*(d-equi_dist)*(d-equi_dist));
+ }
+ }
+
+ return u;
+}
+
+int force_harmonic_oscillator(t_moldyn *moldyn) {
+
+ t_ho_params *params;
+ int i,j,count;
+ t_atom *atom;
+ t_3dvec distance;
+ t_3dvec force;
+ double d;
+ double sc,equi_dist;
+
+ atom=moldyn->atom;
+ count=moldyn->count;
+ params=moldyn->pot_params;
+ sc=params->spring_constant;
+ equi_dist=params->equilibrium_distance;
+
+ for(i=0;i<count;i++) v3_zero(&(atom[i].f));
+
+ for(i=0;i<count;i++) {
+ for(j=0;j<i;j++) {
+ v3_sub(&distance,&(atom[i].r),&(atom[j].r));
+ v3_per_bound(&distance,&(moldyn->dim));
+ d=v3_norm(&distance);
+ if(d<=moldyn->cutoff) {
+ v3_scale(&force,&distance,
+ (-sc*(1.0-(equi_dist/d))));
+ v3_add(&(atom[i].f),&(atom[i].f),&force);
+ v3_sub(&(atom[j].f),&(atom[j].f),&force);
+ }
+ }
+ }
+
+ return 0;
+}
+
+
+/* lennard jones potential & force for one sort of atoms */
+
+double potential_lennard_jones(t_moldyn *moldyn) {
+
+ t_lj_params *params;
+ t_atom *atom;
+ int i,j;
+ int count;
+ t_3dvec distance;
+ double d,help;
+ double u;
+ double eps,sig6,sig12;
+
+ params=moldyn->pot_params;
+ atom=moldyn->atom;
+ count=moldyn->count;
+ eps=params->epsilon;
+ sig6=params->sigma6;
+ sig12=params->sigma12;
+
+ u=0.0;
+ for(i=0;i<count;i++) {
+ for(j=0;j<i;j++) {
+ v3_sub(&distance,&(atom[j].r),&(atom[i].r));
+ d=1.0/v3_absolute_square(&distance); /* 1/r^2 */
+ help=d*d; /* 1/r^4 */
+ help*=d; /* 1/r^6 */
+ d=help*help; /* 1/r^12 */
+ u+=eps*(sig12*d-sig6*help);
+ }
+ }
+
+ return u;
+}
+
+int force_lennard_jones(t_moldyn *moldyn) {
+
+ t_lj_params *params;
+ int i,j,count;
+ t_atom *atom;
+ t_3dvec distance;
+ t_3dvec force;
+ double d,h1,h2;
+ double eps,sig6,sig12;
+
+ atom=moldyn->atom;
+ count=moldyn->count;
+ params=moldyn->pot_params;
+ eps=params->epsilon;
+ sig6=params->sigma6;
+ sig12=params->sigma12;
+
+ for(i=0;i<count;i++) v3_zero(&(atom[i].f));
+
+ for(i=0;i<count;i++) {
+ for(j=0;j<i;j++) {
+ v3_sub(&distance,&(atom[j].r),&(atom[i].r));
+ v3_per_bound(&distance,&(moldyn->dim));
+ d=v3_absolute_square(&distance);
+ if(d<=moldyn->cutoff_square) {
+ h1=1.0/d; /* 1/r^2 */
+ d=h1*h1; /* 1/r^4 */
+ h2=d*d; /* 1/r^8 */
+ h1*=d; /* 1/r^6 */
+ h1*=h2; /* 1/r^14 */
+ h1*=sig12;
+ h2*=sig6;
+ d=12.0*h1-6.0*h2;
+ d*=eps;
+ v3_scale(&force,&distance,d);
+ v3_add(&(atom[j].f),&(atom[j].f),&force);
+ v3_sub(&(atom[i].f),&(atom[i].f),&force);
+ }
+ }
+ }
+
+ return 0;
+}
+
projects / physik / posic.git / blobdiff