__init__.py adding lenard-jones potential

src/python/structurefinder/lj_potential/__init__.py

@@ -11,3 +11,55 @@
 # 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.
+import numpy as np
+import plugandplay as pp
+from simde import TotalEnergy
+
+class LJ_potential(pp.ModuleBase):
+    # Module Construct --------------------------------------------------------
+    def __init__(self):
+        """
+        This module Evaluates the Lennard-Jones 1D potential function (E), and 
+        calculates minus the gradient (Force) in Cartesian coordinates, 
+        according to the relation
+        
+                                 FC = - dE/dx       
+        """
+        pp.ModuleBase.__init__(self)
+        self.description("Lennard-Jones 1D potential function")
+        self.satisfies_property_type(TotalEnergy())
+    #--------------------------------------------------------------------------
+
+    # Module run_ member function ---------------------------------------------
+    def run_(self, inputs):
+        """
+        Parameters
+        ----------
+        inputs : x-coordinate, 
+        TYPE ---> Float
+    
+        Returns
+        -------
+        E: Lennard-Jonnes 1D potential Energy, 
+        TYPE ---> Float 
+        
+        FC: Force in cartesian coordinates evaluated at the given input, 
+        acording to the relation
+                                 FC = - dE/dx  
+        
+        TYPE ---> Float
+        """    
+        pt = TotalEnergy()
+        x0 = pt.unwrap_inputs(inputs)
+        #-------------- LENNARD-JONES FUNCTION --------------------------------
+        E = lambda x: 4*((1/x**12)-(1/x**6))
+        #------------- ANALYTIC FORCE -----------------------------------------        
+        DE_x = -24*((2/x0**13)-(1/x0**7))
+        FC = -DE_x
+        #----------------------------------------------------------------------
+        rv = self.results()    
+        return pt.wrap_results(rv, E,FC)
+    #--------------------------------------------------------------------------
+
+def load_Lenard_Jones_potential(mm):
+    mm.add_module("Lenard-Jones", LJ_potential())