Un schéma pour illustrer l'énergie de liaison

Un schéma pour illustrer l'énergie de liaison, dessiné avec PSTricks par Thomas Söll.

Le code :

\documentclass[12pt,fleqn,dvipsnames]{article}
\usepackage{amsmath}
\usepackage[a4paper,margin=2cm]{geometry}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}

\usepackage{pst-slpe,pst-grad,pst-node,multido}

\begin{document}

\section*{Illustration de l'énergie de liaison}

\def\Kernradius{7.5pt}
\def\KernabstandHe{7.5pt}
\def\ColorProton{BrickRed}
\def\ColorNeutron{gray!60}
\newpsstyle{proton}{linecolor=BrickRed!80,slopebegin=red!30,sloperadius=0.25,linewidth=0.1pt,slopecenter=0.65 0.6,linestyle=solid}
\newpsstyle{neutron}{linecolor=gray!40,slopebegin=white,sloperadius=0.3,linewidth=0.1pt,slopecenter=0.65 0.6,linestyle=solid}
\newpsstyle{atom1}{slopebegin=cyan!90,sloperadius=5.5,slopecenter=0.5 0.5,linestyle=none}
\newpsstyle{atom}{slopebegin=NavyBlue!50,sloperadius=5.5,slopecenter=0.5 0.5,linestyle=none}

\def\Proton{\psBall[style=proton](0,0){\ColorProton}{\Kernradius}}
\def\Neutron{\psBall[style=neutron](0,0){\ColorNeutron}{\Kernradius}}

\def\AtomKernHe{%
\multido{\iAngle=40+180}{2}{%
\rput(\KernabstandHe;\iAngle){\Proton}%
}%
\multido{\iAngle=130+180}{2}{%
\rput(\KernabstandHe;\iAngle){\Neutron}%
}%
}%

\begin{center}
\begin{pspicture}[showgrid=false](-4.25,-3.6)(4,5)
\begin{psclip}{\psframe[linestyle=none](-4.25,-3.4)(4,5)}
\pscustom[fillstyle=solid,fillcolor=orange!60!gray!60,linearc=0.6]{%
\psline(-4.75,4)(0,4)(1,0)(2,0)(3,4)(4.75,4)(4.75,-3.5)(-4.75,-3.5)
\closepath
}
\end{psclip}
\rput(-3.6,4.28){\Proton}
\rput(-3.0,4.28){\Proton}
\rput(-2.4,4.28){\Neutron}
\rput(-1.8,4.28){\Neutron}
\rput(1.5,0.5){\AtomKernHe}

\pcline[nodesepA=0,nodesepB=0,linestyle=dashed,dash=5pt 3pt,linewidth=0.6pt](-1.5,4.28)(1,4.28)
\pcline[nodesepA=0,nodesepB=0,linestyle=dashed,dash=5pt 3pt,linewidth=0.6pt](0,0.5)(1,0.5)
\pcline[nodesepA=0,nodesepB=0,linestyle=dashed,dash=5pt 3pt,linewidth=0.6pt](-1.5,-3.4)(1,-3.4)
{\psset{arrowinset=0.05,arrowscale=1.6,arrowlength=1.8}%
\pcline[linewidth=0.6pt]{<->}(-0.9,-3.4)(-0.9,4.28)
\ncput*[fillcolor=orange!60!gray!60]{$E_{\text{pot,1}}$}
\pcline[linewidth=0.6pt]{<->}(0.4,-3.4)(0.4,0.5)
\ncput*[fillcolor=orange!60!gray!60]{$E_{\text{pot,2}}$}
\pcline[linewidth=0.6pt]{<->}(0.4,0.5)(0.4,4.28)
\ncput{\psframebox[fillstyle=gradient,gradend=orange!60!gray!60,gradbegin=white,gradmidpoint=0,gradangle=100,linestyle=none]{%
$\Delta E_{\text{pot}}$}}

\uput{0.6}[180](-1,-3.45){$E_{\text{pot}} = 0$}
}
\end{pspicture}
\end{center}

\end{document}