git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@11955 f3b2605a-c512-4ea7-a41b-209d697bcdaa

tools/fep/fep.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+# fep.py - calculate free energy from compute fep results
+
+import sys, math
+
+if len(sys.argv) < 2:
+    print "Free Energy Perturbation"
+    print "usage: fep.py temperature < fep.lmp"
+    sys.exit()
+
+rt = 0.008314 / 4.184 * float(sys.argv[1])
+
+v = 1.0
+sum = 0.0
+for line in sys.stdin:
+    if line.startswith("#"):
+        continue
+    tok = line.split()
+    if len(tok) == 4:
+        v = float(tok[3])
+    sum += math.log(float(tok[2]) / v)
+
+print -rt * sum