Subject: Ionization of a molecule...

From: [email-masked] (Wai-To-Chan)
Date: Mon, 15 Nov 1999 18:38:00 -0500 (EST)

I am not sure about the nature of 
the 'potential barrier' to the detachment 
of an electron from an anion you refered to.  
The only such quantity that can measure such 
a barrier I know of is either the
potential term from the Hartree-Fock one-electron 
equation or the one from the exact-one-electron 
schrodinger equation. You may find the discussion from
Yang, Liu and Wang chem phys lett vol 258 pg 30 (1996) 
which shows how the ionization potential of an electron is
related to the limit of the one-electron potential 
at infinite distance from a molecule relevant. In principle you
can determine from visualization of distribution of the potential
where an electron is 'forbidden' or 'allowed' as
well as the barrier to removal of the electron in a molecule.
But I highly doubt such information will be useful for 
spectroscopic measurement.
   
   If I am concerned with 'barrier' to ionization
of an anion I will evaluate the intensity of 
the electron detachment spectrum (like calculating 
the Frank-Condon factor for an electronic excitation 
to determine how 'easy' a transition will take place)
instead.

	I recall seeing reports of calculation of intensity of 
photo electron-detachment spectrum using some deconvolution
method long ago but don't have any references handy with me.
Email me if you are interested in any details. 

Wai-To Chan

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Is there a software package that will calculate the potential
experienced by an electron as the parent molecule is ionized? I.e.,
calculate the energy as an electron is stepped further from the
molecule (which is fixed in the optimized geometry).

I am interested in determining the barrier as a polyanion is ionized.
There is initially an attractive force holding the electron near the
molecule. As the distance between the molecule (anion) and electron is
increased, the dominant force becomes coulomb repulsion. Any
references to published work would be appreciated.

Roy Jensen