Add pair potential and tests

src/box.hpp

@@ -0,0 +1,22 @@
+#ifndef BOX_H
+#define BOX_H
+
+/**
+ * Struct representing the simulation box.
+ * Currently the simulation box is always assumed to be perfectly rectangular.
+ * This code does not support shearing the box. This functionality may be added
+ * in later.
+ */
+template <typename T> struct Box {
+  T xlo;
+  T xhi;
+  T ylo;
+  T yhi;
+  T zlo;
+  T zhi;
+  bool x_is_periodic;
+  bool y_is_periodic;
+  bool z_is_periodic;
+};
+
+#endif