diff --git a/en_disp/en_disp.c b/en_disp/en_disp.c
new file mode 100644
index 0000000..dbd33e8
--- /dev/null
+++ b/en_disp/en_disp.c
@@ -0,0 +1,287 @@
+/*                                    en_disp
+ * Version:                                                                 1.0                   
+ * License:                                                                 GPL
+ * Author:                                          Evgeniy Alexeev aka arcanis
+ * Email:                                                   esalexeev@gmail.com
+ *
+ * 'en_disp' calculate the energy difference between forms with different states 
+ * of a salt bridge.
+ *
+ * Usage:            
+ *                   en_disp -cc FILENAME -no FILENAME [ -ref REF_C-C REF_N-0 ] 
+ *      [ -s NUM_OF_SIMULATION ] [ -p POINTS_IN_SIMULATION ] [ -t TEMPERATURE ] 
+ *                                                       [ -d FILENAME ] [ -h ]
+ *
+ * Compile:
+ *                                                 gcc en_disp.c -o en_disp -lm
+ * Dependence:
+ *      * gcc
+ *      * libs: math.h, stdio.h, stdlib.h, string.h
+ */
+
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// define new RAND_MAX - NOT long int
+#ifdef RAND_MAX
+#undef RAND_MAX
+#define RAND_MAX 100000
+#endif
+
+
+double cc_ref, no_ref, temp;
+double dist[50000][2];
+int distrib_exists[50000], points, points_in_model, total_points;
+/* cc_ref           - reference distance for C-C
+ * dist             - distance between atoms
+ * distrib_exists   - array of number of points when ionic lock exists
+ * no_ref           - reference distance for N-O
+ * points           - number of simulations
+ * points_in_model  - number of points in single simulation
+ * temp             - temperature
+ * total_points     - trajectory length
+ */
+
+
+void analyze()
+{
+// function to analyze distributions
+  double aver=0.0, disp=0.0, t_ratio;
+  int i;
+/* aver             - average energy
+ * disp             - standard deviation
+ * t_ratio          - ratio of t(exists) to t(broken)
+ */
+
+  for (i=0; i<points; i++)
+  {
+    t_ratio = points_in_model - distrib_exists[i];
+    t_ratio = distrib_exists[i] / t_ratio;
+    aver += log(t_ratio);
+  }
+  aver = -1.99 * temp * aver / points;
+  
+  for (i=0; i<points; i++)
+  {
+    disp += pow((-1.99 * temp * log(t_ratio) - aver), 2);
+  }
+  disp = sqrt(disp / (points - 1));
+  
+  printf ("Energy: %5.2f +- %4.2f ccal/mol\n", aver/1000, disp/1000);
+}
+
+
+void calc()
+{
+// function to calculate initial system energy
+  double ener, t_ratio;
+  int exists=0, i;
+/* ener             - energy
+ * t_rato           - ratio of t(exists) to t(broken)
+ * exists           - time when ionic lock exists
+ */
+
+  for (i=0; i<total_points; i++)
+    if ((dist[i][0] <= cc_ref) && (dist[i][1] <= no_ref))
+      exists++;
+  printf ("Ionic lock exists: %4i ns\n", exists);
+  
+  t_ratio = total_points - exists;
+  t_ratio = exists / t_ratio;
+  ener = -1.99 * temp * log(t_ratio);
+  printf ("Initial trajectory energy: %5.2f ccal/mol\n", ener/1000);
+}
+
+
+void disp(int iter)
+{
+// function to create distributions
+  int i=0, index;
+
+  for (i=0; i<points_in_model; i++)
+  {
+    // max of index is ~(total_points-1)
+    index = rand() % ((RAND_MAX % total_points)+1);
+    if ((dist[index][0] <= cc_ref) && (dist[index][1] <= no_ref))
+      distrib_exists[iter]++;
+  }
+}
+
+
+void print_distr(char out_name[])
+{
+// function to print received simulations
+  int i;
+  FILE *out;
+
+  out = fopen(out_name, "w+");
+  for (i=0; i<points; i++)
+    fprintf(out, "%i\n", distrib_exists[i]);
+  fclose(out);
+}
+
+
+void reading(char inp_name[], int choice)
+{
+// function to read input data
+// choice           - equal 0 if C-C or equal 1 if N-O
+  int i=0;
+  FILE *inp;
+
+  inp = fopen(inp_name, "r+");
+  if (inp == NULL)
+  {
+    printf ("File '%s' doesn't exists\nExiting\n", inp_name);
+    exit(1);
+  }
+  
+  while (!feof(inp))
+  {
+    fscanf (inp, "%lf", &dist[i][choice]);
+    i++;
+  }
+  total_points = i;
+  
+  fclose(inp);
+}
+
+
+void zeroing()
+{
+// function to zeroing of variables
+  int i;
+  
+  cc_ref = 9.0;
+  no_ref = 3.0;
+  temp = 313.0;
+  points = 300;
+  points_in_model = 250;
+  for (i=0; i<50000; i++)
+    distrib_exists[i] = 0;
+}
+
+
+int main(int argc, char *argv[])
+{
+  char distrib_out_name[256];
+  int distrib_out=0, error_label=0, i;
+  FILE *inp;
+/* distrib_out      - equal 1 if print results or equal 1 if not
+ * distrib_out_name - filename with results
+ * error_label      - label for checking error in input files
+ */
+
+  printf ("Starting program '%s'\n", argv[0]);
+
+  printf ("\n1) Zeroing");
+  zeroing();
+  printf ("%41s\n", "done\n");
+    
+  printf ("2) Reading arguments\n");
+  if (argc == 1)
+  {
+    printf ("Arguments aren't set\nType 'en_disp -h' for help message\nExiting\n");
+    return 1;
+  }
+  
+  for (i=1; i<argc; i++)
+  {
+    if ((argv[i][0] == '-') && (argv[i][1] == 'c') && (argv[i][2] == 'c'))
+    {
+      printf ("Reading file '%s'\n", argv[i+1]);
+      reading(argv[i+1], 0);
+      error_label++;
+      i++;
+    }
+    if ((argv[i][0] == '-') && (argv[i][1] == 'n') && (argv[i][2] == 'o'))
+    {
+      printf ("Reading file '%s'\n", argv[i+1]);
+      reading(argv[i+1], 1);
+      error_label++;
+      i++;
+    }
+    if ((argv[i][0] == '-') && (argv[i][1] == 'r') && (argv[i][2] == 'e') && (argv[i][3] == 'f'))
+    {
+      cc_ref = atof(argv[i+1]);
+      no_ref = atof(argv[i+2]);
+      i += 2;
+    }
+    if ((argv[i][0] == '-') && (argv[i][1] == 's'))
+    {
+      points = atoi(argv[i+1]);
+      i++;
+    }
+    if ((argv[i][0] == '-') && (argv[i][1] == 'p'))
+    {
+      points_in_model = atoi(argv[i+1]);
+      i++;
+    }
+    if ((argv[i][0] == '-') && (argv[i][1] == 't'))
+    {
+      temp = atof(argv[i+1]);
+      i++;
+    }
+    if ((argv[i][0] == '-') && (argv[i][1] == 'd'))
+    {
+      distrib_out = 1;
+      strcpy(distrib_out_name, argv[i+1]);
+      i++;
+    }
+    if ((argv[i][0] == '-') && (argv[i][1] == 'h'))
+    {
+      printf ("Usage: en_disp -cc FILENAME -no FILENAME [ -ref REF_C-C REF_N-0 ]\
+ [ -s NUM_OF_SIMULATION ] [ -p POINTS_IN_SIMULATION ] [ -t TEMPERATURE ]\
+ [ -d FILENAME ] [ -h ]\n\n");
+      printf ("  -cc    - input file with C-C distance\n");
+      printf ("  -no    - input file with N-O distance\n");
+      printf ("  -ref   - reference distance, A. Default is 9.0 and 3.0 A\n");
+      printf ("  -s     - number of simulation for distribution. Default is 300\n");
+      printf ("  -p     - number of points in distribution simulation. Default is 250\n");
+      printf ("  -t     - temperature, K. Default is 313 K\n");
+      printf ("  -d     - print distribution in file %%FILENAME%%\n");
+      printf ("  -h     - show this help and exit\n");
+      return 0;
+    }
+  }
+  
+// error check
+  if (error_label < 2)
+  {
+    printf ("Input files aren't set\nType 'en_disp -h' for help message\nExiting\n");
+    return 1;
+  }
+
+  printf ("Parametrs:\n");
+  printf ("  C-C reference, A                = %5.2f\n", cc_ref);
+  printf ("  N-O reference, A                = %5.2f\n", no_ref);
+  printf ("  Number of simulation            = %5i\n", points);
+  printf ("  Number of points in simulation  = %5i\n", points_in_model);
+  printf ("  Temperature, K                  = %5.1f\n", temp);
+  
+  printf ("%50s\n", "done");
+  
+  printf ("\n3) Calculating\n");
+  calc();
+  printf ("%50s\n", "done");
+  
+  printf ("\n4) Simulation");
+  for (i=0; i<points; i++)
+    disp(i);
+  if (distrib_out == 1)
+  {
+    printf ("\nPrint distribution to file '%s'\n%50s\n", distrib_out_name, "done");
+    print_distr(distrib_out_name);
+  }
+  else
+    printf ("%37s\n", "done");
+  
+  printf ("\n5) Analyzing\n");
+  analyze();
+  printf ("%50s\n", "done");
+  
+  
+  printf ("\nExiting without errors\n");
+  return 0; 
+}