Re: CCL:Re:REPLY TO HOW TO FIND BONDS

Dear CCL
 On the subject of defining a bond:
 The 'Atoms in Molecules' methodology of Richard Bader
 provides an objective means to define atoms and bonds,
 thereby linking chemical intuition with quantum mechanics.
 Check out the site
     http://www.chemistry.mcmaster.ca/faculty/bader/aim/
 it is very informative.
 elewars wrote:
 > Hello,
 >
 > So far as I know there is no "true definition" of a bond. At one
 level the concept is simple, at another level sophisticated. Given
 > the cartesian coordinates of a molecule, the simplest way to get the
 "bonds" is to draw a line between all pairs of nuclei within a
 > distance that experience or general agreement says is bonding; there are
 programs that will do this (e.g. Molwin, some versions of
 > Spartan). This shows you what the molecule looks like, which is sometimes
 all you want.
 > Of course bonds can be assigned from calculated bond order, determined by
 the coefficients of the basis functions in the occupied
 > MOs (e.g. Lo:wdin B.O., Meyer B.O., Mulliken B. O), or from an analysis of
 the calculated electron density: AIM analysis--atoms in
 > molecules (Bader analysis).
 >
 > EL
 > =====
 >
 > li guo hui wrote:
 >
 > > Dear Netters:
 > > i would like to know what is the true definition of bond, this
 question can also be given in the following:
 > > given a file only including coordinates of atoms in molecule, there
 are not connectivities between atoms in molecule, just from
 > > this file how can i find the bonds or connectivities? using Van der
 walls radius or covalance radius of atoms or some results of
 > > population analysis from theoretical calcualtion?
 > >
 > > thank you
 > >
 > >
 > > Li Guo Hui
 > > State Key Laboratory of Molecular Reaction Dynamics
 > > Dalian Institute of Chemical Physics
 > > Liao Ning Province, P.R.China
 > >
 > > Mailing Address:
 > > Room 715
 > > Xing Hai Third Street, 59 #
 > > Sha He Kou District
 > > Dalian, Liaoning Province
 > > P.R.China, 116023
 > >
 >
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