Single point calculation without gradients

ASE
1

Dear ASE community,

Is there a way to do single point calculation without asking the external program to run also the gradients?

I make my self clearer, I’m trying to run SP calculation at DLPNO-CCSD(T) level, unfortunately when I add the calculator and ask for the energy:

geom.calc = SimpleQMMM(qmindex,ORCA(label='0_grain_SP_DLPNO_orca', orcasimpleinput='DLPNO-CCSD(T) aug-cc-pVTZ aug-cc-pVTZ/C TightPNO NumGrad', orcablocks='%pal nprocs 36 end \n %maxcore 6000'),
                   mace_off(model="large", device='cpu'), mace_off(model="large", device='cpu'), vacuum=None)
energy=geom.get_potential_energy()
print(energy)

It generates the following ORCA input:

! engrad DLPNO-CCSD(T) aug-cc-pVTZ aug-cc-pVTZ/C TightPNO NumGrad
%pal nprocs 36 end
 %maxcore 2000
*xyz 0 1
....
....*structure*....
...

Is there a way to ask ASE only to generate a SP calculation in ORCA? In the manual of ORCA you can find these keywords:

-ENERGY
-SP

2

I’m not familiar with Orca but it looks like you are asking it to calculate the forces with NumGrad in your orcasimpleinput section?

3

Hi, no I put it because otherwise the calculation would crush due to the fact that there are not Analytical gradient for coupled cluster calculation. It behaves exactly the same also without the “NumGrad” keyword in the input

4

I see, so the “engrad” is the issue.

It looks like the last release version of ASE inserts this keyword, but about a year ago the code was changed so that it no longer does this:

I suggest that you switch to a development build of ASE until the next release, hopefully that will solve your problem.

5

Thank you!!!