Hi Wade, How big is the DelPhi file you are trying to open with DelPhi Viewer in Chimera? Could you send me the Python traceback you get? In addition to the DelPhi Viewer extension you can use the Volume Viewer extension (Extensions/Volumes/Volume Viewer) to look at a DelPhi electrostatics. If you try to open a *.phi file with the Chimera open file dialog it will use Volume Viewer. Volume Viewer can show electrostatic potential isosurfaces. For electrostatics, you may want to show positive and negative isosurfaces in different colors. Using ctrl-click in the Volume Viewer dialog histogram you can add a second threshold level to make a negative potential surface, and you can give it a different color with the color button. One thing the DelPhi Viewer does that Volume Viewer does not do is color a molecular surface. So we would like to get DelPhi Viewer working for you. Tom