molecule m;
float 	x[2000], f[2000], v[2000];
float 	dgrad, fret;
float	t1,t2;
int 	ier; 

m = getpdb("gbrna.pdb");
readparm(m, "gbrna.prmtop");
mm_options( "ntpr=100, gb=1, kappa=0.10395, cut=99.0, diel=C, tempi=300., rattle=0");
mme_init( m, NULL, "::Z", x, NULL);

setxyz_from_mol( m, NULL, x );
t1 = second();
ier = md(3*m.natoms, 1000, x, f, v, mme );
t2 = second();
printf( "md returns %d; elapsed time was %8.3f\n", ier, t2-t1 );
putxv( "gbrna_long.x", "rattle md", m.natoms, 0.0, x, v );