Cfrgtkky

I'm trying to draw an MO diagram for CH2 by mimicking this MO diagram (excluding the orbital images), but things don't look like the way I want it to be. I really want to make it nice and similar to the image, but what I'm doing right now just seems sad and would really appreciate it if someone can help me.

I tried using MOdiagram package, but needs A LOT of work on it, especially with the overall size of the diagram because it is too small when I typeset. So, it would be really nice if someone can help me. Please and thank you.

documentclass{article}

usepackage{modiagram}

usepackage[version=4]{mhchem}

begin{document}



begin{MOdiagram}[labels-fs=scriptsize]

        AO(1cm){s}[label={2s}]{0.5;}

        AO(-0.4cm){p}[label={2p}]{2;}

        node at (1cm, -1){C};

        %%%%%%%%%%%%%%%%%%%%%%%

        AO(3cm){s}[label={$2mathrm{a}_1$}]{0;pair}

        AO(3cm){s}[label={1e}]{0.9;pair} 

        AO(3cm){s}{1.1;pair} 

        AO(3cm){s}[label={$3mathrm{a}_1$}]{2;pair}

        AO(3cm){s}[label={$4mathrm{a}_1$}]{3;}

        AO(3cm){s}[label={2e}]{3.9;}

        AO(3cm){s}{4.1;}

        node at (3cm, -1){ce{CH_2}};

        %%%%%%%%%%%%%%%%%%%%%%%

        AO(5cm){s}[label={1s}]{2.5;}

        node at (5cm, -1){H};

end{MOdiagram}





end{document}

I haven't used MOdiagram before, but as you tagged the question tikz-pgf, here is a (simple) pure TikZ solution.

I am not even using a chemistry package and writing BeH₂ as BeH$_2$
:) but you really should change that in your document.

documentclass[tikz,margin=3mm]{standalone}

begin{document}

begin{tikzpicture}

draw[dotted] (-3,0)--(-.3,3)--(.3,3)--(4,-1)--(.3,-4.5)--(-.3,-4.5)--cycle;

draw[dotted] (-3,-1.5)--(-.3,1.5)--(.3,1.5)--(4,-2)--(.3,-6.5)--(-.3,-6.5)--cycle;

draw[thick] (-.3,3)--(.3,3) (-.3,1.5)--(.3,1.5) (-.8,0)--(-.2,0) (.2,0)--(.8,0) (-.3,-4.5)--(.3,-4.5) (-.3,-6.5)--(.3,-6.5) (-3,0)--(-3.6,0) node[midway,below] {$2p_z$} (-3.8,0)--(-4.4,0) node[midway,below] {$2p_y$} (-4.6,0)--(-5.2,0) node[midway,below] {$2p_x$} (-3,-1.5)--(-3.6,-1.5) node[midway,below] {$2s$} (4,-2)--(4.6,-2) node[midway,below] {$Phi_mathrm g$} (4,-1)--(4.6,-1) node[midway,below] {$Phi_mathrm u$};

draw[dotted] (-4.6,0)--(1.9,0);

draw (0,0) node[below] {$pi_mathrm u^mathrm n$};

draw (0,.75) node {$sigma^*_mathrm g$};

draw (0,2.25) node {$sigma^*_mathrm u$};

draw (0,-5.5) node {$sigma_mathrm u$};

draw (0,-4.5) node {rotatebox{90}{$rightleftharpoons$}};

draw (0,-6.5) node {rotatebox{90}{$rightleftharpoons$}};

draw (0,-7) node {$sigma_mathrm g$};

draw (-4.2,4) node {Be};

draw (0,4) node {BeH$_2$};

draw (4.2,4) node {2 H (textsc{salc}s)};

end{tikzpicture}

end{document}