ATC version 2.0, date: Aug7

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@10561 f3b2605a-c512-4ea7-a41b-209d697bcdaa
2013-08-07 21:34:54 +00:00
parent fafff431e9
commit 7855ef6dda
195 changed files with 83477 additions and 4499 deletions
--- a/lib/atc/CbLjSmoothLinear.h
+++ b/lib/atc/CbLjSmoothLinear.h
@ -0,0 +1,88 @@
+#ifndef CBLJSMOOTHLINEAR_H
+#define CBLJSMOOTHLINEAR_H
+
+#include <iostream>
+#include <cstdlib>
+#include "CbPotential.h"
+namespace ATC
+{
+
+  /**
+   *  @class  CbLjSmoothLinear
+   *  @brief  Class for computing Cauchy-Born quantities for a Lennard-Jones/smooth/linear  material
+   *          (A factor of one-half is already included to split the
+   *           bond energy between atoms)
+   */
+
+  class CbLjSmoothLinear : public CbPotential
+  {
+  public:
+    //! Constructor - initializes coefficients and enables PAIRWISE term.
+    CbLjSmoothLinear(double eps, double sig, double cutoff_radius)
+      : CbPotential(Interactions(PAIRWISE)),
+        A  (4.0*eps*pow(sig, 12)),
+        B  (4.0*eps*pow(sig,  6)),
+        rcut(cutoff_radius)
+    { 
+      ricut = 1.0/rcut;
+      r6icut = (ricut*ricut*ricut)*(ricut*ricut*ricut); 
+      phicut = r6icut*(A*r6icut - B);
+      dphicut = r6icut*ricut*(6.0*B - 12.0*A*r6icut); 
+    }
+    
+    //! Returns the cutoff readius of the LJ potential.
+    double cutoff_radius() const { return rcut; }
+    //! Returns the LJ energy between two interacting atoms (6,12).
+    double phi(const double &r) const 
+    {
+      const double r6i = 1.0/((r*r*r)*(r*r*r));
+      if (r < rcut) { 
+        return (r6i*(A*r6i - B) - phicut - (r-rcut)*dphicut);
+      }
+      else {
+        return 0.0;
+      }
+    }
+    //! Returns the first derivative of the LJ energy (7,13).
+    double phi_r(const double &r) const 
+    {
+      const double ri  = 1.0/r;
+      const double r6i = (ri*ri*ri)*(ri*ri*ri);
+      if (r < rcut) { 
+        return (r6i*ri*(6.0*B - 12.0*A*r6i) - dphicut);
+      }
+      else {
+        return 0.0;
+      }
+    }
+    //! Returns the second derivative of the LJ energy (8,14).
+    double phi_rr(const double &r) const 
+    {
+      const double r2i = 1.0/(r*r);
+      const double r6i = r2i*r2i*r2i;
+      if (r < rcut) {
+        return r6i*r2i*(13.0*12.0*A*r6i - 7.0*6.0*B);
+      }
+      else {
+        return 0.0;
+      }
+    }
+    //! Returns the third derivative of the LJ bond energy (9,15).
+    double phi_rrr(const double &r) const
+    {
+      const double r3i = 1.0/(r*r*r);
+      const double r9i = r3i*r3i*r3i;
+      if (r < rcut) {
+        return r9i*(8.0*7.0*6.0*B - 14.0*13.0*12.0*A*r3i*r3i);
+      }
+      else {
+        return 0.0;
+      }
+    }
+
+    const double A, B;  //!< phi  =  Ar^-12 +    Br^-6
+    const double rcut;  //!< cutoff radius
+    double ricut, r6icut, phicut, dphicut;
+  };
+}
+#endif