Re: [AMBER] About constraints on QM system of QM/MM simulation

From: Marc van der Kamp <>
Date: Wed, 18 Jan 2017 22:14:24 +0000

No, it does not mean that. The phrase just indicates what mechanical
embedding offers you: Freedom of movement of QM atoms is limited by nearby
MM atoms, through VdW interactions.
You can always use restraints on QM atoms (harmonic or otherwise) in the
same way you can for pure MM simulations.
Note that mechanical embedding is far inferior to mechanical+electrostatic
embedding for most/all applications.


On 18 Jan 2017 22:04, "Pengfei Li" <> wrote:

Hello everyone,

I have a quick question about doing QM/MM calculations with AMBER and
Q-Chem. In the page 142 of Amber16 manual it said: "Mechanical embedding is
useful to impose steric constraints on the embedded QM system” (after
equation 10.4), does this mean the electrostatic embedding strategy is not
applicable when someone want to add steric constraints (for example using
harmonic constraints) on the atoms in the QM region? Thanks!

Best regards,
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