%%cpp -d

#include <cmath>

double WaveFunction(double x, double y) {
   double r = sqrt(x *x + y*y);

   double w = (1/pow((4*sqrt(2*TMath::Pi())* 1), 1.5)) * (2 - (r / 1)*pow(TMath::E(), (-1 * r)/2)); // Wavefunction formula for psi 2,0,0

   return w*w; // Amplitude

}

TH2F *h2D = new TH2F("Hydrogen Atom",
                     "Hydrogen in n = 2, l = 0, m = 0 state; Position in x direction; Position in y direction",
                     200, -10, 10, 200, -10, 10);

for (float i = -10; i < 10; i += 0.01) {
   for (float j = -10; j < 10; j += 0.01) {
      h2D->Fill(i, j, WaveFunction(i, j));
   }
}

gStyle->SetPalette(kCividis);
gStyle->SetOptStat(0);

TCanvas *c1 = new TCanvas("c1", "Schroedinger's Hydrogen Atom", 750, 1500);
c1->Divide(1, 2);

auto c1_1 = c1->cd(1);
c1_1->SetRightMargin(0.14);
h2D->GetXaxis()->SetLabelSize(0.03);
h2D->GetYaxis()->SetLabelSize(0.03);
h2D->GetZaxis()->SetLabelSize(0.03);
h2D->SetContour(50);
h2D->Draw("colz");

TLatex *l = new TLatex(-10, -12.43, "The Electron is more likely to be found in the yellow areas and less likely to be found in the blue areas.");
l->SetTextFont(42);
l->SetTextSize(0.02);
l->Draw();

auto c1_2 = c1->cd(2);
c1_2->SetTheta(42.);

TH2D *h2Dc = (TH2D*)h2D->Clone();
h2Dc->SetTitle("3D view of probability amplitude;;");
h2Dc->Draw("surf2");

gROOT->GetListOfCanvases()->Draw()