Ham4LVLReg1 = ({
         {0, 0, 0, [CapitalOmega]a1[t]},
         {0, 0, 0, [CapitalOmega]b1[t]},
         {0, 0, 0, [CapitalOmega]c1[t]},
         {[CapitalOmega]a1[t], [CapitalOmega]b1[t], [CapitalOmega]c1[
           t], 2 [CapitalDelta]}
        })/2;

    Evecs = Eigenvectors[Ham4LVLReg1];
    E1 = Eigenvectors[Ham4LVLReg1][[1]];
    E2 = Eigenvectors[Ham4LVLReg1][[2]];

    [Lambda]1 = E1/Sqrt[E1.E1];
    [Lambda]2a = Orthogonalize[{E1, E2}][[2]];
    [Lambda]2 = [Lambda]2a/Sqrt[[Lambda]2a.[Lambda]2a];