On 6/3/13 7:49 PM, tnorgd wrote:
Dear group,
I am not sure how SPC energy actually works - is there really just one VdW
interaction - just between two oxygen atoms?
Yep. A lot of force fields work like that. Given the size of H atoms relative
to their heavy atom counterparts, the heavy atom to which they are connected
generally governs the vdW interactions.
If so, when I place a hydrogen atom of one water molecule at the location of
the oxygen from another water,
the two oxygens are separated by the distance of H-O bond length i.e. 1.0A.
The only VdW interaction is repulsive but finite (and equal ~4E6) but the
electrostatic between H and O is -Inf = 1/0.0
What's wrong?
Nothing. That makes perfect sense. You're introducing atomic overlap and thus
an energetic singularity from the infinite Coulombic attraction.
-Justin
--
========================================
Justin A. Lemkul, Ph.D.
Research Scientist
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
========================================
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