I installed Chem3d v 20.0 (windows 10) and already have GAMESS 2019 installed in the default directory (\users\public\gamess-64\). When I installed Chem3d, I checked to
see that the gamess-us interface was checked for install. I also checked the preferences that
"Always display claculation interface menuitems..." was checked.

The problem is that under the Calculations tab, only Diherdal driver, extended huckel, and MM2 are showing. Please point me in the direction to get Chem3d to show the GAMESS interface.

Thanks

From v18.0 we have two installers one for Windows platform (i.e cos18x.exe/cos19x.exe/cos20.x) and one for Mac platform (i.e cd18x.dmg/cd19x.dmg/cd200.dmg) and the product activated based on the activation code .

If you use ChemDraw Professional activation code Chem3D application activate and works in the Pro level (without GAMESS, MOPAC and Gaussian Interfaces under Calculation menu)

On the other hand if you use ChemOffice Professional activation code Chem3D application activate and works in the Ultra level (with GAMESS, MOPAC and Gaussian Interfaces)

So we recommend to check your Chem3D level (Ultra or Pro). You can get that by the following way.
1. Open Chem3D 20.0
2. Go to the Help menu and choose the “About Chem3D”
3. This will open up another window containing information like level (Ultra or Pro), version etc.

Currently we support GAMESS 2018, please retest the problem (if you have Chem3D Ultra) with GAMESS 2018.

You will find the installation steps in the following FAQ
http://informatics.perkinelmer.com/Support/KnowledgeBase/details/Default?TechNote=3734

- PKI Support