From: Monika Madhavi (
Date: Sun Jan 24 2016 - 23:31:07 CST

Dear all,

I want to select all the inter-molecular hydrogen atoms within a sphere of
radius 5A from a central hydrogen atom. Coordinates of the central atom are
x1,y1,z1. I tried this atomselect command.

set sel1 [atomselect $mol "name "H.*" and
sqrt(sqr(x-$x1)+sqr(y-$y1)+sqr(z-$z1)) < 5"]

this gives me an error saying "extra characters after quoted text"

Please help me to resolve this problem.

Thank you.

W.A.Monika Madhavi
Lecturer (Probation),
Department of Physics,
University of Colombo.