On 5/9/19 6:54 AM, Sabreen Farnaz wrote:
Dear Users,
It is known that electric dipole moment of a water monomer is
experimentally 1.85 D and using the TIP3P model it's supposed to be 2.35D.
I am using the TIP3P model for a water-based simulation in Gromacs 5.1.5.
After applying sinusoidal electric fields in the Y axis, the norm of the
dipole vector per water molecule using *gmx dipoles* is closer to 1.85 D
and nowhere near 2.35D. My simulations are for 300K and 1 atm.
Can anyone guess why the discrepancy? Is it because 2.35D is for a water
monomer and my system has quite a large number of them(in the order of ten
thousands)? But literature suggests that presence of water molecules should
enhance the dipole moment. Or is 2.35D calculated under a different
temperature/pressure conditions?
I don't know what your command was or how gmx dipoles might be
calculating this quantity, but it is simply a fact that the dipole
moment of rigid TIP3P is 2.35 D. It can't vary, by definition. You will
not see any difference based on system size because the model is
nonpolarizable - every TIP3P is identical, whether you have one or a
million, so there is no dipole cooperativity.
-Justin
--
==
Justin A. Lemkul, Ph.D.
Assistant Professor
Office: 301 Fralin Hall
Lab: 303 Engel Hall
Virginia Tech Department of Biochemistry
340 West Campus Dr.
Blacksburg, VA 24061
jalem...@vt.edu | (540) 231-3129
http://www.thelemkullab.com
==
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