diff --git a/MindSPONGE/mindsponge/md/__init__.py b/MindSPONGE/mindsponge/md/__init__.py
index b2d8c553adfff55b2095c98c36bd9470b5f7d213..c30947cf455d8000e52edc4f7bdcb74a64544432 100644
--- a/MindSPONGE/mindsponge/md/__init__.py
+++ b/MindSPONGE/mindsponge/md/__init__.py
@@ -13,31 +13,16 @@
 # limitations under the License.
 # ============================================================================
 """simulation md"""
-# Copyright 2020-2021 Huawei Technologies Co., Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-# ============================================================================
-"""simulation"""
 
-from . import potential
 from . import control
-from . import space
 from . import partition
-from .functions import *
-from .potential import *
+from . import potential
+from . import space
 from .control import *
-from .space import *
 from .partition import *
+from .potential import *
+from .space import *
+
 
 __all__ = []