From: Sujata Roy (
Date: Thu Dec 04 2014 - 23:17:53 CST

Dear all,

We are trying to calculate the electrostatic interaction energy between a
hydrogen on a beta-carbon and a carboxylate oxygen of closely located
aspartic acid residues using VMD 'measure energy'.

When measure energy elect {atom1 atom2} is given as the command it returns
a highly positive value indicating repulsive interactions.

When measure energy elect {atom1 atom2} q1 0.96 q2 -0.76 is used, it
returns a negative value indicating attractive interaction.

May we know why this difference in this value occurs? (since
hydrogen-oxygen interactions are usually attractive in nature.)

Your answer will be very much helpful to us.

Thanking you.

Sujata Roy