Re: [AMBER] printcharges using Amber24 GFN2-xtB method

From: Niven Singh via AMBER <amber.ambermd.org>
Date: Fri, 17 May 2024 23:26:51 +0000

Hi,

Thanks so much! This prints out mulliken charges for all atoms in the QM region.

I had another question about xTB in Amber24. When the calculation finishes, there's a XTBESCF= ___ (floating point) in the qmmm.out file. Is this a single point energy? And what are the units?

If I use an older version of amber and interface xTB2 with orca, there is a XTBESCF= in qmmm.out but also a FINAL SINGLE POINT ENERGY in old.orc_job.tpl file. Are these two energies related or separate? And are both in hartrees?

I'm assuming the two numbers are related but I'm not sure how.

Thanks so much!
Niven 🙂
________________________________
From: Timothy Giese via AMBER <amber.ambermd.org>
Sent: Wednesday, May 15, 2024 11:51 AM
To: amber.ambermd.org <amber.ambermd.org>
Subject: Re: [AMBER] printcharges using Amber24 GFN2-xtB method

The issue being described doesn't appear to be related to GFN2-xTB. The symptom exists when qm_theory is changed to DFTB2, for example. The printcharges=1 output is disabled in runmin.F90 when imin=5. To accomplish your task, you can instead set the following options in &cntrl: "imin=6, ntpr=1, nstlim=1". You should then see output that looks like "Atomic Charges for Step 1 :".
-Tim

> I'm trying to use QM/MM with Amber24 using the GFN2-xtB method for a single point calculation. I'm trying to print out the Mulliken charges so I can see how the program has spread the qm_charge across the QM subsystem but when I set printcharges to 1, I don't see the charges per atom for my subsystem in the output file.
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Received on Fri May 17 2024 - 16:30:02 PDT
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