diff --git a/source/train/DescrptSeA.py b/source/train/DescrptSeA.py
index 890fe24672..e46265231f 100644
--- a/source/train/DescrptSeA.py
+++ b/source/train/DescrptSeA.py
@@ -17,6 +17,7 @@ def __init__ (self, jdata):
                .add('resnet_dt',bool,   default = False) \
                .add('trainable',bool,   default = True) \
                .add('seed',     int) \
+               .add('type_one_side', bool, default = False) \
                .add('exclude_types', list, default = []) \
                .add('set_davg_zero', bool, default = False) \
                .add('activation_function', str,    default = 'tanh') \
@@ -39,6 +40,9 @@ def __init__ (self, jdata):
             self.exclude_types.add((tt[0], tt[1]))
             self.exclude_types.add((tt[1], tt[0]))
         self.set_davg_zero = class_data['set_davg_zero']
+        self.type_one_side = class_data['type_one_side']
+        if self.type_one_side and len(exclude_types) != 0:
+            raise RuntimeError('"type_one_side" is not compatible with "exclude_types"')
 
         # descrpt config
         self.sel_r = [ 0 for ii in range(len(self.sel_a)) ]
@@ -244,17 +248,27 @@ def _pass_filter(self,
         inputs = tf.reshape(inputs, [-1, self.ndescrpt * natoms[0]])
         output = []
         output_qmat = []
-        for type_i in range(self.ntypes):
-            inputs_i = tf.slice (inputs,
-                                 [ 0, start_index*      self.ndescrpt],
-                                 [-1, natoms[2+type_i]* self.ndescrpt] )
+        if not self.type_one_side:
+            for type_i in range(self.ntypes):
+                inputs_i = tf.slice (inputs,
+                                     [ 0, start_index*      self.ndescrpt],
+                                     [-1, natoms[2+type_i]* self.ndescrpt] )
+                inputs_i = tf.reshape(inputs_i, [-1, self.ndescrpt])
+                layer, qmat = self._filter(tf.cast(inputs_i, self.filter_precision), type_i, name='filter_type_'+str(type_i)+suffix, natoms=natoms, reuse=reuse, seed = self.seed, trainable = trainable, activation_fn = self.filter_activation_fn)
+                layer = tf.reshape(layer, [tf.shape(inputs)[0], natoms[2+type_i] * self.get_dim_out()])
+                qmat  = tf.reshape(qmat,  [tf.shape(inputs)[0], natoms[2+type_i] * self.get_dim_rot_mat_1() * 3])
+                output.append(layer)
+                output_qmat.append(qmat)
+                start_index += natoms[2+type_i]
+        else :
+            inputs_i = inputs
             inputs_i = tf.reshape(inputs_i, [-1, self.ndescrpt])
-            layer, qmat = self._filter(tf.cast(inputs_i, self.filter_precision), type_i, name='filter_type_'+str(type_i)+suffix, natoms=natoms, reuse=reuse, seed = self.seed, trainable = trainable, activation_fn = self.filter_activation_fn)
-            layer = tf.reshape(layer, [tf.shape(inputs)[0], natoms[2+type_i] * self.get_dim_out()])
-            qmat  = tf.reshape(qmat,  [tf.shape(inputs)[0], natoms[2+type_i] * self.get_dim_rot_mat_1() * 3])
+            type_i = -1
+            layer, qmat = self._filter(tf.cast(inputs_i, self.filter_precision), type_i, name='filter_type_all'+suffix, natoms=natoms, reuse=reuse, seed = self.seed, trainable = trainable, activation_fn = self.filter_activation_fn)
+            layer = tf.reshape(layer, [tf.shape(inputs)[0], natoms[0] * self.get_dim_out()])
+            qmat  = tf.reshape(qmat,  [tf.shape(inputs)[0], natoms[0] * self.get_dim_rot_mat_1() * 3])
             output.append(layer)
             output_qmat.append(qmat)
-            start_index += natoms[2+type_i]
         output = tf.concat(output, axis = 1)
         output_qmat = tf.concat(output_qmat, axis = 1)
         return output, output_qmat