Add Maxwell-Boltzmann method for velocities

src/md/System.hpp

@@ -11,33 +11,58 @@
 
 #pragma once
 
+#include <functional>
 #include <vector>
 
 #include "Atom.hpp"
 
+typedef std::function<double(double)> PotentialFunction;
+typedef std::function<double(double)> ForceFunction;
+
 class System {
 private:
   std::vector<Atom> atoms;    ///< Atoms in the system
   std::vector<Atom> atomsOld; ///< Atoms in the system in the previous step
 
+  std::vector<double> forceTable;     ///< Force table
+  std::vector<double> forceTableOld;  ///< Force table in the previous step
+  std::vector<double> potentialTable; ///< Potential table
+
+  ForceFunction     forceGenerator;     ///< Force generator
+  PotentialFunction potentialGenerator; ///< Potential generator
+
+  double rcut;  ///< Cutoff radius
+  double rcut2; ///< Cutoff radius squared
+
+  std::size_t tableResolution = 1000; ///< Resolution of the force table
+
   double timeDelta = 0; ///< Time delta between steps
 
   /**
-   * @brief Initialize the force table
+   * @brief Initialize the force and potential tables
    *
    */
-  void initForceTable();
+  void initTables();
 
   /**
-   * @brief Initialize the potential table
+   * @brief Evaluate interaction forces between atoms
    *
    */
-  void initPotentialTable();
+  void evaulateForces();
 
 public:
-  explicit System(double timeDelta);
+  explicit System(double            timeDelta,
+                  double            rcut,
+                  PotentialFunction potentialFunction,
+                  ForceFunction     forceFunction,
+                  std::size_t       tableResolution = 1000);
 
   void step();
+
+  /**
+   * @brief Step the system to the first step using euler method
+   *
+   */
   void stepFirst();
 
   /**