Molcas Forum

CZJ

Member

Registered: 2025-02-18

Posts: 1

&LAST_ENERGY modul

Dear all,

I am curious about why there is no &LAST_ENERGY module when optimizing a conical intersection. I tried adding a keyword (details about the input are provided below) in SLAPAF, but it did not work. Does anyone know how I can achieve this? The issue is that I need to repeat this optimization process many times, and I don’t want to "waste" time running single-point calculations.

I've included in my input:

>>>COPY $HomeDir/LASTEN LASTEN 

&slapaf
iter=300
LASTENERGY=CASPT2

Thank you in advanced,
CZJ.

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,088

Re: &LAST_ENERGY modul

That's because LAST_ENERGY runs an energy calculation for a new updated geometry. After the optimization is converged (gradient and displacement are small), the energy is computed for the geometry after such small displacement.

In the case of a conical intersection, small geometry changes will (should) not affect significantly the energy or CI characterization, but may affect dramatically the orbital or electronic state analysis. Since it's often important to have orbital files that correspond the the CI that has been characterized, the "last energy" calculation is automatically skipped in CI optimizations.

You can probably save that additional single-point calculation if you set MOLCAS_REDUCE_PRT=NO, then you'll have a normal printout for all the energy calculations during the optimization, and you can just look at the last one before convergence.