fix changes in ase optimizer API

Author: yanghan234

src/mattersim/applications/batch_relax.py

@@ -122,7 +122,10 @@ def step_batch(self):
 
                 opt.step()
                 opt.nsteps += 1
-                if opt.converged() or opt.nsteps >= self.max_n_steps:
+                # Get gradient for convergence check
+                # Note: gradient = -forces for the optimizable object
+                gradient = opt.optimizable.get_gradient()
+                if opt.converged(gradient) or opt.nsteps >= self.max_n_steps:
                     self.is_active_instance[idx] = False
                     self.total_converged += 1
                     if self.total_converged % 100 == 0: