# return json.loads(self.ssbond)
unres_ff = models.CharField(max_length=20,choices=FF_CHOICE,default='E0LL2Y')
+ pdbcode = models.CharField(max_length=4,default='')
# minimization
min_choice = models.CharField(max_length=20,choices=MIN_CHOICE,default='minimize cart')
min_overlap = models.BooleanField(default=False)