For paramagnetic simulation (no pair interaction declared), the "atom_modify" command has to be used (in order to initialize the bin).

example: atom_modify sort 1000 4.0 (Freq. of sorting, Cutoff distance)

In order to print the actual time with the total mag., the vector associated to the mag. compute was modified. It is now: [time, Mx, My, Mz, |M|, En_mag]

Optimization of the spin_compute routine: energy and mag. have been gathered in a same loop.

in.cobalt

@@ -10,13 +10,14 @@ units metal
 dimension 3
 
 #setting boundary conditions. (p for periodic, f for fixed, ...)
-boundary p p p 
+#boundary p p p 
 #boundary f f f
 
 #setting atom_style, defines what can of atoms to use in simulation (atomic, molecule, angle, dipole, ...)
 atom_style spin
 #atom_style hybrid sphere spin
 
+atom_modify sort 1000 4.0
 
 ###########################
 #######Create atoms########
@@ -27,7 +28,7 @@ lattice fcc 3.54
 
 #Defining a geometric region of space. Sets ID(user's choice), style(block, sphere, ...), then, args depends on the style chosen
 #(for block, one has x0, xf, y0, yf, z0, zf, in distance units)
-region box block 0.0 2.0 0.0 2.0 0.0 2.0
+region box block 0.0 1.0 0.0 1.0 0.0 1.0
 
 #Creating a simulation box based on the specified region. Entries: number of atom types and box ref. 
 create_box 1 box
@@ -50,18 +51,18 @@ mass		1 1.0
 #set		group all mass 1.0
 #Setting spins orientation and moment 
 #set group all spin/random 11 1.7
-set group all spin 1.7 0.0 1.0 0.0 
+set group all spin 1.7 1.0 0.0 0.0 
 
 #Magnetic exchange interaction coefficient for bulk fcc Cobalt
-pair_style pair/spin 4.0
-pair_coeff * * 0.0446928 0.003496 1.4885
+#pair_style pair/spin 4.0
+#pair_coeff * * 0.0446928 0.003496 1.4885
 #pair_coeff * * 0.0 0.003496 1.4885
 
 #Fix Langevin spins (merging damping and temperature)
 #Defines a cutof distance for the neighbors. 
 #neighbor 0.5 bin
 #Magnetic field fix
-fix 1 all force/spin zeeman 50 0.0 0.0 1.0
+fix 1 all force/spin zeeman 10 0.0 0.0 1.0
 #fix 1 all force/spin zeeman 0.0 0.0 0.0 1.0
 #fix 1 all force/spin anisotropy 0.1 0.0 0.0 1.0
 
@@ -74,13 +75,13 @@ fix 3 all nve/spin
 
 #compute total magnetization and magnetic energy
 compute mag all compute/spin
-fix outmag all ave/time 1 1 100 c_mag[1] c_mag[2] c_mag[3] c_mag[4] c_mag[5]  file mag.dat
+fix outmag all ave/time 1 1 50 c_mag[1] c_mag[2] c_mag[3] c_mag[4] c_mag[5] c_mag[6] file mag.dat
 
 #Defining a computation that will be performed on a group of atoms. 
 #Entries: ID(user assigned), group-ID(group of atoms to peform the sim on), style(temp, pe, ...), args    
 
 #Setting the timestep for the simulation
-timestep	0.000005
+timestep	0.00005
 
 ##################
 #######run########
@@ -90,6 +91,6 @@ timestep	0.000005
 dump 1 all custom 100 dump_spin.lammpstrj type x y z spx spy spz
 
 #Running the simulations for N timesteps
-run 10
-
+run 1000000
+#run 100
 

src/SPIN/compute_spin.cpp

@@ -32,7 +32,7 @@ ComputeSpin::ComputeSpin(LAMMPS *lmp, int narg, char **arg) :
   if ((narg != 3) && (narg != 4)) error->all(FLERR,"Illegal compute compute/spin command");
 
   vector_flag = 1;
-  size_vector = 5;
+  size_vector = 6;
   extvector = 0;
 
   init();
@@ -61,7 +61,7 @@ void ComputeSpin::compute_vector()
   int i, index;
   
   invoked_vector = update->ntimestep;
-
+  
   countsp = countsptot = 0.0;	
   mag[0] = mag[1] = mag[2] = mag[3] = 0.0; 
   magtot[0] = magtot[1] = magtot[2] = magtot[3] = 0.0; 
@@ -77,13 +77,16 @@ void ComputeSpin::compute_vector()
 	
   int nlocal = atom->nlocal;
     
-  // compute total magnetization  
+  // compute total magnetization and magnetic energy 
   for (i = 0; i < nlocal; i++) {
     if (mask[i] & groupbit) {
       if (atom->mumag_flag && atom->sp_flag) {
 		mag[0] += sp[i][0];
 		mag[1] += sp[i][1];
 		mag[2] += sp[i][2];
+		magenergy += mumag[i]*sp[i][0]*fm[i][0];  
+		magenergy += mumag[i]*sp[i][1]*fm[i][1]; 
+		magenergy += mumag[i]*sp[i][2]*fm[i][2]; 		
 		countsp++;
                 }
       }
@@ -91,6 +94,7 @@ void ComputeSpin::compute_vector()
   }
   
   MPI_Allreduce(mag,magtot,4,MPI_DOUBLE,MPI_SUM,world);
+  MPI_Allreduce(&magenergy,&magenergytot,1,MPI_DOUBLE,MPI_SUM,world);
   MPI_Allreduce(&countsp,&countsptot,1,MPI_DOUBLE,MPI_SUM,world);
   
   double scale = 1.0/countsptot;
@@ -99,25 +103,12 @@ void ComputeSpin::compute_vector()
   magtot[2] *= scale;    
   magtot[3] = sqrt(square(magtot[0])+square(magtot[1])+square(magtot[2]));
  
-  // compute total magnetic energy 
-  for (i = 0; i < nlocal; i++) {
-    if (mask[i] & groupbit) {
-      if (atom->mumag_flag && atom->sp_flag) {
-		magenergy += mumag[i]*sp[i][0]*fm[i][0];  
-		magenergy += mumag[i]*sp[i][1]*fm[i][1]; 
-		magenergy += mumag[i]*sp[i][2]*fm[i][2]; 		
-      }
-      else error->all(FLERR,"Compute spin/compute declared magnetic quantities (sp and mumag flags)");
-    }
-  }
-  
-  MPI_Allreduce(&magenergy,&magenergytot,1,MPI_DOUBLE,MPI_SUM,world);
- 
-  vector[0] = magtot[0];
-  vector[1] = magtot[1];
-  vector[2] = magtot[2];
-  vector[3] = magtot[3];
-  vector[4] = magenergytot;  
+  vector[0] = invoked_vector*update->dt;
+  vector[1] = magtot[0];
+  vector[2] = magtot[1];
+  vector[3] = magtot[2];
+  vector[4] = magtot[3];
+  vector[5] = magenergytot;  
 }
 
 /* ----------------------------------------------------------------------
@@ -129,6 +120,6 @@ void ComputeSpin::allocate()
   memory->destroy(mag);
   memory->create(mag,4,"compute/spin:mag");
   memory->create(magtot,5,"compute/spin:mag");
-  vector = magtot;
+  memory->create(vector,6,"compute/spin:vector");
 }
 

src/SPIN/fix_force_spin.cpp

@@ -189,7 +189,7 @@ void FixForceSpin::post_force(int vflag)
 		  //emag -= (sp[i][0]*fm[i][0] + sp[i][1]*fm[i][1] + sp[i][2]*fm[i][2]);
 	  }
   }
-  //printf("test force. 1;i=0, fx=%g, fy=%g, fz=%g \n",fm[0][0],fm[0][1],fm[0][2]); 
+  printf("test force. 1;i=0, fx=%g, fy=%g, fz=%g \n",fm[0][0],fm[0][1],fm[0][2]); 
   //printf("Field force compute, fm[0][2]=%g \n",fm[0][2]); 
 }
 

vmd_nano.vmd

@@ -70,7 +70,7 @@ proc enable_trace {} {
      trace variable vmd_frame([molinfo top]) w vmd_draw_spin    
      }
      
-set molid [mol addfile {/ascldap/users/jtranch/Documents/Test_lammps_Spin3/src/dump_spin.lammpstrj} type {lammpstrj} autobonds off first 0 last -1 step 1 waitfor all]
+set molid [mol addfile {/home/jtranch/Documents/lammps/src/dump_spin.lammpstrj} type {lammpstrj} autobonds off first 0 last -1 step 1 waitfor all]
 scale by 0.5
 animate style Loop
 enable_trace