[gmx-users] Salt bridges

[Andrea Carotti]

Hi all,
I've a general question: could someone tell me at which distance an ion pair 
interaction could be considered a salt bridge?
I've read from a paper that:
"Two charged residues in a protein are inferred to form salt bridges if 1) 
their side-chain charged
group centroids are within a 4-Å distance and 2) at least one pair of 
side-chain nitrogen and oxygen atoms in the
two residues are within a 4-Å distance."
Is this a good definition and so...could I use the -t option of g_saltbr 
with a value of 0.4 ?
I'll really appreciate any comment
Andrea