Solutions in C up to 2.2

.gitignore

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+plt_dat
+data

hydrogen.h

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+#include <math.h>
+#include <stdio.h>
+
+double potential(double *r, const int l) {
+      double pot;
+
+      pot = 0.0;
+      for (int i = 0; i < l; ++i) {
+	    pot += r[i] * r[i];
+      }
+
+      if (pot > 0.0) {
+	   return -1.0 / sqrt(pot); 
+      }
+      return -1;
+
+}
+
+double psi(double a, double *r, const int l) {
+      double psival, rnorm;
+
+      psival = 0.0;
+      rnorm = 0.0;
+      for (int i = 0; i < l; ++i) {
+	    rnorm += r[i]*r[i];
+      }
+      rnorm = sqrt(rnorm);
+
+      psival = exp(-a * rnorm);
+
+      return psival;
+}
+
+double kinetic(double a, double *r, const int l) {
+      double rnorm;
+
+      for (int i = 0; i < l; ++i) {
+	    rnorm += r[i]*r[i];
+      }
+      rnorm = sqrt(rnorm);
+
+      return a * (1 / rnorm - 0.5 * a);
+      
+}
+
+double e_loc(double a, double *r, const int l) {
+      return kinetic(a, r, l) + potential(r, l);
+}

plot_hydrogen.c

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+#include "hydrogen.h"
+
+int main() {
+      const double a[6] = {0.1, 0.2, 0.5, 1., 1.5, 2.};
+      const int sizex = 50;
+      double x[sizex], dx;
+
+      dx = 10.0 / (sizex - 1);
+      for (int i = 0; i < sizex; ++i) {
+	    x[i] = -5.0 + (i - 1) * dx;
+      }
+
+      FILE * fil;
+
+      fil = fopen("./data", "w+");
+
+      for (int i; i < 6; ++i) {
+	    for (int j = 0; j < sizex; ++j) {
+		  fprintf(fil, "%lf %lf\n", x[j], e_loc(a[i], &x[j], 1)); 
+	    }
+	    fprintf(fil, "\n\n");
+      }
+
+      fclose(fil);
+
+      return 0;
+}