diff --git a/src/molearn/trainers/openmm_physics_trainer.py b/src/molearn/trainers/openmm_physics_trainer.py
index 61917e2..37b1979 100644
--- a/src/molearn/trainers/openmm_physics_trainer.py
+++ b/src/molearn/trainers/openmm_physics_trainer.py
@@ -1,6 +1,29 @@
 import torch
 from molearn.loss_functions import openmm_energy
 from .trainer import Trainer
+import os
+
+
+soft_xml_script='''\
+<ForceField>
+ <Script>
+import openmm as mm
+nb = mm.CustomNonbondedForce('C/((r/0.2)^4+1)')
+nb.addGlobalParameter('C', 1.0)
+sys.addForce(nb)
+for i in range(sys.getNumParticles()):
+    nb.addParticle([])
+exclusions = set()
+for bond in data.bonds:
+    exclusions.add((min(bond.atom1, bond.atom2), max(bond.atom1, bond.atom2)))
+for angle in data.angles:
+    exclusions.add((min(angle[0], angle[2]), max(angle[0], angle[2])))
+for a1, a2 in exclusions:
+    nb.addExclusion(a1, a2)
+ </Script>
+</ForceField>
+'''
+
 
 
 class OpenMM_Physics_Trainer(Trainer):
@@ -12,8 +35,8 @@ class OpenMM_Physics_Trainer(Trainer):
     '''
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-
-    def prepare_physics(self, physics_scaling_factor=0.1, clamp_threshold=1e8, clamp=False, start_physics_at=0, **kwargs):
+        
+    def prepare_physics(self, physics_scaling_factor=0.1, clamp_threshold=1e8, clamp=False, start_physics_at=0, xml_file = None, soft_NB = True, **kwargs):
         '''
         Create ``self.physics_loss`` object from :func:`loss_functions.openmm_energy <molearn.loss_functions.openmm_energy>`
         Needs ``self.mol``, ``self.std``, and ``self._data.atoms`` to have been set with :func:`Trainer.set_data<molearn.trainer.Trainer.set_data>`
@@ -25,13 +48,24 @@ def prepare_physics(self, physics_scaling_factor=0.1, clamp_threshold=1e8, clamp
         :param \*\*kwargs: All aditional kwargs will be passed to :func:`openmm_energy <molearn.loss_functions.openmm_energy>`
 
         '''
+        if xml_file is None and soft_NB==True:
+            print('using soft nonbonded forces by default')
+            from molearn.utils import random_string
+            tmp_filename = f'soft_nonbonded_{random_string()}.xml'
+            with open(tmp_filename, 'w') as f:
+                f.write(soft_xml_script)
+            xml_file = ['amber14-all.xml', tmp_filename]
+            kwargs['remove_NB'] = True
+        elif xml_file is None:
+            xml_file = ['amber14-all.xml']
         self.start_physics_at = start_physics_at
         self.psf = physics_scaling_factor
         if clamp:
             clamp_kwargs = dict(max=clamp_threshold, min=-clamp_threshold)
         else:
             clamp_kwargs = None
-        self.physics_loss = openmm_energy(self.mol, self.std, clamp=clamp_kwargs, platform='CUDA' if self.device == torch.device('cuda') else 'Reference', atoms=self._data.atoms, **kwargs)
+        self.physics_loss = openmm_energy(self.mol, self.std, clamp=clamp_kwargs, platform='CUDA' if self.device == torch.device('cuda') else 'Reference', atoms=self._data.atoms, xml_file = xml_file, **kwargs)
+        os.remove(tmp_filename)
 
     def common_physics_step(self, batch, latent):
         '''
diff --git a/src/molearn/trainers/trainer.py b/src/molearn/trainers/trainer.py
index 950dd6c..866e6a1 100644
--- a/src/molearn/trainers/trainer.py
+++ b/src/molearn/trainers/trainer.py
@@ -138,7 +138,18 @@ def scheduler_step(self, logs):
         '''
         pass
 
-    def run(self, max_epochs=100, log_filename=None, log_folder=None, checkpoint_frequency=1, checkpoint_folder='checkpoint_folder', allow_n_failures=10, verbose=None):
+    def prepare_logs(self, log_filename, log_folder=None):
+        self.log_filename = log_filename
+        if log_folder is not None:
+            if not os.path.exists(log_folder):
+                os.mkdir(log_folder)
+            if hasattr(self, "_repeat") and self._repeat >0:
+                self.log_filename = f'{log_folder}/{self._repeat}_{self.log_filename}'
+            else:
+                self.log_filename = f'{log_folder}/{self.log_filename}'
+
+
+    def run(self, max_epochs=100, log_filename=None, log_folder=None, checkpoint_frequency=1, checkpoint_folder='checkpoint_folder', allow_n_failures=10, verbose=None, allow_grad_in_valid=False):
         '''
         Calls the following in a loop:
 
@@ -158,12 +169,14 @@ def run(self, max_epochs=100, log_filename=None, log_folder=None, checkpoint_fre
         :param bool verbose: (default: None) set trainer.verbose. If True, the epoch logs will be printed as well as written to log_filename 
 
         '''
-        if log_filename is not None:
-            self.log_filename = log_filename
-            if log_folder is not None:
-                if not os.path.exists(log_folder):
-                    os.mkdir(log_folder)
-                self.log_filename = log_folder+'/'+self.log_filename
+        self.get_repeat(checkpoint_folder)
+        self.prepare_logs(log_filename if log_filename is not None else self.log_filename, log_folder)
+        #if log_filename is not None:
+        #    self.log_filename = log_filename
+        #    if log_folder is not None:
+        #        if not os.path.exists(log_folder):
+        #            os.mkdir(log_folder)
+        #        self.log_filename = log_folder+'/'+self.log_filename
         if verbose is not None:
             self.verbose = verbose
 
@@ -173,8 +186,11 @@ def run(self, max_epochs=100, log_filename=None, log_folder=None, checkpoint_fre
                     time1 = time.time()
                     logs = self.train_epoch(epoch)
                     time2 = time.time()
-                    with torch.no_grad():
+                    if allow_grad_in_valid:
                         logs.update(self.valid_epoch(epoch))
+                    else:
+                        with torch.no_grad():
+                            logs.update(self.valid_epoch(epoch))
                     time3 = time.time()
                     self.scheduler_step(logs)
                     if self.best is None or self.best > logs['valid_loss']:
@@ -381,11 +397,11 @@ def checkpoint(self, epoch, valid_logs, checkpoint_folder, loss_key='valid_loss'
                     'atoms': self._data.atoms,
                     'std': self.std,
                     'mean': self.mean},
-                   f'{checkpoint_folder}/last.ckpt')
+                   f'{checkpoint_folder}/last{f"_{self._repeat}" if self._repeat > 0 else ""}.ckpt')
 
         if self.best is None or self.best > valid_loss:
-            filename = f'{checkpoint_folder}/checkpoint_epoch{epoch}_loss{valid_loss}.ckpt'
-            shutil.copyfile(f'{checkpoint_folder}/last.ckpt', filename)
+            filename = f'{checkpoint_folder}/checkpoint{f"_{self._repeat}" if self._repeat>0 else ""}_epoch{epoch}_loss{valid_loss}.ckpt'
+            shutil.copyfile(f'{checkpoint_folder}/last{f"_{self._repeat}" if self._repeat>0 else ""}.ckpt', filename)
             if self.best is not None:
                 os.remove(self.best_name)
             self.best_name = filename
@@ -424,6 +440,20 @@ def load_checkpoint(self, checkpoint_name='best', checkpoint_folder='', load_opt
         epoch = checkpoint['epoch']
         self.epoch = epoch+1
 
+    def get_repeat(self, checkpoint_folder):
+        if not os.path.exists(checkpoint_folder):
+            os.mkdir(checkpoint_folder)
+        if not hasattr(self, '_repeat'):
+            self._repeat = 0
+            for i in range(1000):
+                if not os.path.exists(checkpoint_folder+f'/last{f"_{self._repeat}" if self._repeat>0 else ""}.ckpt'):
+                    break#os.mkdir(checkpoint_folder)
+                else:
+                    self._repeat += 1
+            else:
+                raise Exception('Something went wrong, you surely havnt done 1000 repeats?')
+
+
 
 if __name__=='__main__':
     pass