Re: [AMBER] Explicit understanding the force computed from U(CMAP) term

From: David Cerutti <>
Date: Fri, 6 Sep 2019 04:28:58 -0400

You've got two dihedral angles, A-B-C-D and B-C-D-E. The potential energy
is computed using bicubic spline interpolation on a grid of values,
typically 24 x 24 point in each direction (the potential is known at 15
degree intervals, and interpolated based on that). The forces on atoms are
computed form the derivatives of that bicubic spline interpolation, which
must then be transmuted via the chain rule back to Cartesian space on each
of the atoms.



On Thu, Sep 5, 2019 at 6:35 PM Lod King <> wrote:

> Hi Amber
> How to explicitly understand the force computed from U(CMAP) energy term. I
> have been reading the papers "Mackerell, Feig, and Brooks Vol. 25, No. 11
> Journal of Computational Chemistry" and "Martin Karplus 1995 Journal of
> Computational Chemistry", and still having difficulty understanding the
> math applied here.
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Received on Fri Sep 06 2019 - 01:30:01 PDT
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