Geometric methods for the most general Ginzburg-Landau model with two   order parameters
  The Landau potential in the general Ginzburg-Landau theory with two order parameters and all possible quadratic and quartic terms cannot be minimized with the straightforward algebra. Here, a geometric approach is presented that circumvents this computational difficulty and allows one to get insight into many properties of the model in the mean-field approximation. 
I. P. Ivanov