Subject: pi stacking area calculations again

From: <[email-masked]>
Date: Tue, 31 Oct 1995 19:23:14 MET-DST

Dear CCL Netters,

Last week I posted to the CCL inquiring with the following problem:

Does anybody know for some program applicable to crystals or molecules with pi
stacking interactions, that calculate area of the aromatic molecule or fragment
covered by the neighbour aromatic molecule or fragment?

Since I have no answers to summarize the subject, and supposing my question 
was not precise enough, I am asking for help on the pi stacking area 
calculations:
   Suppose one have several solved crystal structures or extracted from 
Cambridge Structural Database, or molecules are built and optimized by
molecular mechanics or quantum mechanics programs. If these molecules are 
partially or completely aromatic, then it is possible that
neighbour molecules or aromatic fragments are mutually parallel and on the
distance approximately 3.5 A. If one can find a suitable view normal to the 
aromatic planes, stacking could be observed as covering of one aromatic system
by one or two neighbour system. By changing the relative positional parameters
of the neighbour aromatic systems this covering is changed. In the first 
approximation it could be taken that measure of this covering is area of the
observed aromatic system (the system is taken as planar hexagons) or surface
area (the system is supposed to be three-dimensional in pi interactions, 
and the interacting surface is not a plane containing the hexagons).
The question is: 
Is there any program or appropriate reference dealing with such or similar 
calculations of the covering (pi stacking) areas or surface areas for a
specified set of relative positional parameters?
Any information or suggestion is welcome. Thanks in advance.

Rudolf
-------------

Rudolf Kiralj
Department of Materials Science and Electronics
Rudjer Boskovic Institute
Bijenicka 54
10 000 Zagreb
Croatia
e-mail: [email-masked]