(* W.Quapp, 2010 *)
(* Model PES nach NFK, modified by 0.03, see CPL 2004, JCC 2010submitted *)
 
 pes[x_,y_]= 0.03*(x^2+y^2)^2+
 x*y-9.0*Exp[-(x-3.0)^2-y^2]-9.0*Exp[-(x+3.0)^2-y^2]

 con=ContourPlot[pes[x,y],{x,-0.81,3.31},{y,-3.31,0.81},
    Contours->30,PlotLabel-> "Ridge Downhill",
    ContourShading->False,PlotPoints->79,
    ContourStyle->Thickness[0.001] ] 

 p1[x_,y_]=D[pes[x,y], x] 
 p3[x_,y_]=D[pes[x,y], y] 
 p33[x_,y_]=D[p3[x,y], y] 
 p31[x_,y_]=D[p3[x,y], x] 
 p11[x_,y_]=D[p1[x,y], x]

 grad[x_,y_]={p1[x,y],p3[x,y]}
 
 Adj[x_,y_]={{p33[x,y],-p31[x,y]},{-p31[x,y],p11[x,y]}}
 
 xi[x_,y_]= grad[x,y].Adj[x,y].grad[x,y]
 
 conxi=ContourPlot[xi[x,y],{x,-0.81,3.31},{y,-3.31,0.81},
   ContourShading->False,PlotPoints->130,Contours->{0.0},
   ContourStyle->{Dashing[{0.01,0.01}],Thickness[0.001]}]  
 
 ge[x_,y_]=p31[x,y]* (p1[x,y]^2 -p3[x,y]^2) +
         (p33[x,y]- p11[x,y])*p3[x,y] *p1[x,y] 

 conge=ContourPlot[ge[x,y],{x,-0.81,2.01},{y,-3.01,0.81},
   ContourShading->False,PlotPoints->191,Contours->{0.0},
   ContourStyle->Thickness[0.008] ]
 conge2=ContourPlot[ge[x,y],{x,2.01,3.01},{y,-2.35,-0.16},
   ContourShading->False,PlotPoints->191,Contours->{0.0},
   ContourStyle->Thickness[0.008] ]

 xx=Show[Graphics[{
 Text["Min",{2.75, 0.0}], Point[{0,0}],
 Text["SP", {0.24, 0.0}], Point[{0,0}]},
 PlotRange->{{-0.8,3.2},{-3.2,0.8}}]];

 WEG=<<chain.dat; 
 P1=ListPlot[WEG,PlotJoined->True]
 P2=ListPlot[WEG,PlotStyle->PointSize[0.013]]

 x11= Show[con,conxi,conge,conge2,P1,P2,xx,
  FrameLabel->{"x","y"}, AspectRatio->Automatic,
  FormatType -> TraditionalForm,
  TextStyle->{FontFamily->Arial,FontSize->24}]