Calculating electronic preparation energy using ALMO-EDA

I’m trying to reproduce the non-Aufbau ALMO-EDA calculations for Ba+(CO) from webinar 39. On slide 26 of the presentation I can see the preparation energy required to promote an electron from the Barium 6s orbital to 5d is 67.8 kJ/mol. I understand the concept of the preparation energy, I would like to know how this number was obtained.

Also I can’t seem to find any information in the Q-Chem manual on specifying the non-Aufbau configurations using the $SCFMI_MOM keyword, will this information be made available soon?

Thanks for your question. Indeed, with the Q-Chem job shown in the webinar only, one will not be able to get this preparation energy that captures the promotion from 6s to 5d. The simplest way to get this number is to first look for the “Fragment Energies” section in the output of this non-aufbau ALMO-EDA job, in which you will be able to find the energy of the Ba+ fragment in the 5d configuration. Then you can run a standard ground-state SCF calculation for Ba+, which will provide the energy for the aufbau 6s state. You can also choose to run an additional EDA calculation without the “eda2_mom” keyword and then look for its fragment energy section.

I haven’t put this feature into the manual mainly because I used to have a plan to publish this method. However, for some reason this plan has been suspended. Therefore, I will consider adding the documentation of this scheme to Q-Chem manual with the upcoming 5.4 release.