? about NIST material names

Hello all,

Sorry for my stupid question. I am evaluating import of GDML geometries in GEANT4 and I have found
strange thing. When I am using the standard material names like G4_Si, G4_O etc, I get report that material not exists

when I try to check it debug mode, I see that NIST manages uses material names like “H, C, O etc” without “G4_” prefix…

So, what material names I should use??

I’m also rather new in G4 but could you provide the code where you are making use of these materials? I’m also stumbling over similar issues but got it running for my first needs.
If I see it correctly above it is the source code, right?

Despite the error message, I believe the correct material is actually constructed by Geant. One way to double check is to issue the UI command /vis/drawTree which will list the volume and density of each logical volume (you may have to increase the verbosity to something like 3 or 4 using /vis/ASCIITree/verbose). I get the correct densities, despite the error being issued upon reading the GDML file.