Dear Eric,
As far as I see from the code, you should also subtract the “Self energy of the charges” (as found in the Gaussian output) to match EXTERNESCF.
Probably to avoid double counting. (?)
EXTERNESCF = E(RwB97XD) - self_energy
Best,
Antoine
____________________________
-- Dr. Antoine MARION
Assistant Professor
Doktor Öğretim Üyesi
Department of Chemistry
Middle East Technical University
06800, Ankara, Turkey
Office: O-310
Email: amarion.metu.edu.tr <mailto:amarion.metu.edu.tr>
Phone: +90 312 210 51 44
> On 4 Dec 2018, at 14:36, Eric Lang <eric.lang.bristol.ac.uk> wrote:
>
> Dear Amber Developers and Users,
>
>
>
> I am running some single point QM/MM in Sander (compiled as Amber16+AmberTools17) using Gaussian 09.
>
> The calculations run ok, but I think something is not quite right with the extraction of the QM energy from the gaussian output file: the EXTERNESCF energy in the mdout file in kcal/mol doesn’t match the final energy (last ‘SCF Done’ line or ‘HF’ at the very end of the Gaussian file) when converted to kcal/mol using the conversion used in Amber (AU_TO_KCAL = 6.2750946943E+02).
>
> I would think they should be the same.
>
> Am I missing something obvious in the way the calculations are done or is there a problem with the way the gaussian output files are parsed?
>
>
>
> Here is the output form Amber:
>
>
>
> FINAL RESULTS
>
> NSTEP ENERGY RMS GMAX NAME NUMBER
>
> 1 -5.0519E+05 1.3953E+01 1.1652E+02 CA 1579
>
>
>
> BOND = 456.4977 ANGLE = 1327.2559 DIHED = 2177.6750
>
> VDWAALS = 8267.2236 EEL = -89612.1756 HBOND = 0.0000
>
> 1-4 VDW = 625.9136 1-4 EEL = 7948.6914 RESTRAINT = 0.0000
>
> EXTERNESCF = -436379.7510
>
>
>
> And here is the final energy from Gaussian
>
>
>
> SCF Done: E(RwB97XD) = -3178.95512525 A.U.
>
>
>
> Which gives -1994824.4 kcal/mol and not -436379.7510 kcal/mol as found in EXTERNESCF.
>
>
>
> Many thanks in advance for your help,
>
>
>
> Eric
>
>
>
> --
>
> Eric Lang
>
> Centre for Computational Chemistry
> School of Chemistry - University of Bristol
> Bristol BS8 1TS - United Kingdom
>
>
>
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Received on Tue Dec 04 2018 - 06:30:02 PST
