On Tue, May 23, 2023, Alan Chien via AMBER wrote:
>
>I'm trying to determine the details of the QMMM coupling scheme used in the
>sander module when doing semi-empirical (PM6, AM1, etc) calculations.
>Specifically, the manual doesn't detail the form of h_core in equation
>10.3.
h_core is determined by the QM method itself, since the gas-phase results
for each method match those published by the original authors.
I'm not sure what paper you are referring to here. The most detailed
description of what is in Amber is here: Walker, Crowley, Case, J. Comput.
Chem. 29:1019 (2008). But it doesn't have any Eq. 10.3
I'm not expert on semi-empirical QM, but I would have thought that h_core is
just a point charge, placed at the atomic nucleus, with a charge of Z-Ncore,
where Ncore is the number of core electrons.
....hope this helps....dac
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Received on Wed May 24 2023 - 05:00:03 PDT
