From owner-chemistry@ccl.net Sun Jun 10 03:18:00 2012
From: "bonoit bonoit bonoit_10/a\yahoo.fr" <owner-chemistry%server.ccl.net>
To: CCL
Subject: CCL: Contribution from vibrational motion
Message-Id: <-47063-120610031442-10340-nA2fGerkjOFQAmTO1QDp4g%server.ccl.net>
X-Original-From: "bonoit  bonoit" <bonoit_10,,yahoo.fr>
Date: Sun, 10 Jun 2012 03:14:40 -0400


Sent to CCL by: "bonoit  bonoit" [bonoit_10-*-yahoo.fr]
Dear CClers,
For calculating the Contribution from vibrational motion, we have two ways to choose the zero of energy: either the bottom of the internuclear potential energy well, or the first vibrational level.
What is the difference between them?
When can we use one and the other? and why?
Regards
Bonoit


From owner-chemistry@ccl.net Sun Jun 10 08:01:00 2012
From: "Christina Jenifer msc christinamsc##gmail.com" <owner-chemistry**server.ccl.net>
To: CCL
Subject: CCL:G: TDDFT how to find out the particular transition & orbital
Message-Id: <-47064-120610032953-1811-eIMAdVTXintOwPkzbC26Pw**server.ccl.net>
X-Original-From: "Christina Jenifer msc" <christinamsc() gmail.com>
Date: Sun, 10 Jun 2012 03:29:51 -0400


Sent to CCL by: "Christina Jenifer msc" [christinamsc]|[gmail.com]
Dear CClers
	My studies involve TDDFT calculation of curtain Pyrene like molecule using Gaussian software. I would like to know how to find out the particular transition is   *, -*, etc. and also how to find out which orbital (1B1u, 1Bu, 1Ag, 1Bu, 1B1, 1B2, 1A1, 1A2, etc.) is responsible for the particular transition. Can you explain me briefly? Kindly help me in this regard.

Thanks in advance

With Regards
Christina


From owner-chemistry@ccl.net Sun Jun 10 08:36:00 2012
From: "Elham Abdolhamidi flight.66.ab#%#gmail.com" <owner-chemistry[*]server.ccl.net>
To: CCL
Subject: CCL:G: finding bandstructure in gaussian
Message-Id: <-47065-120610052558-23562-01WEz4bek1QV8m63gQ19tg[*]server.ccl.net>
X-Original-From: "Elham  Abdolhamidi" <flight.66.ab|,|gmail.com>
Date: Sun, 10 Jun 2012 05:25:56 -0400


Sent to CCL by: "Elham  Abdolhamidi" [flight.66.ab-.-gmail.com]
Dear members;
I'm using gaussian and I want to find the band structure(E-k diagram) of Polypyrrole.I wanted to know if I have to use PBC for drawing this polymer in gaussview or I can use clipboard & draw the polymer and then find the band structure.
In other words, I want to know if using PBC is mandatory in finding the band structure or not.
Regards,
Elham


From owner-chemistry@ccl.net Sun Jun 10 21:10:00 2012
From: "Geoffrey Hutchison geoffh|pitt.edu" <owner-chemistry . server.ccl.net>
To: CCL
Subject: CCL: finding bandstructure in gaussian
Message-Id: <-47066-120610210840-16621-jnlS4A+kGAABFwyLtFuLwg . server.ccl.net>
X-Original-From: Geoffrey Hutchison <geoffh!=!pitt.edu>
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Date: Sun, 10 Jun 2012 21:08:36 -0400
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Sent to CCL by: Geoffrey Hutchison [geoffh=-=pitt.edu]
> In other words, I want to know if using PBC is mandatory in finding the band structure or not.

Yes. The idea of "band structure" (i.e., where the energy levels are infinitesimally close) doesn't make sense outside of the context of an infinite system. You could approximate it with some huge oligomer, but why? The calculation would be much less efficient than using PBC.

Of course the band structure of polypyrrole is published. From home, I can't look for other sources, but here's the one-dimensional band diagram:
Phys. Rev. B (2003) vol 68, art. 035204
DOI: 10.1103/PhysRevB.68.035204

Hope that helps,
-Geoff

---
Prof. Geoffrey Hutchison
Department of Chemistry
University of Pittsburgh
tel: (412) 648-0492
email: geoffh[*]pitt.edu
web: http://hutchison.chem.pitt.edu/