From owner-chemistry@ccl.net Sun Dec 6 14:07:01 2009
From: "Geoffrey Hutchison geoffh{:}pitt.edu" <owner-chemistry[A]server.ccl.net>
To: CCL
Subject: CCL:G: how to build a polythiophene unit cell for a pbc gaussian calculation
Message-Id: <-40871-091206140017-22972-NDaxASCS/q4W9rW4NM6U1Q[A]server.ccl.net>
X-Original-From: Geoffrey Hutchison <geoffh:+:pitt.edu>
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Date: Sun, 06 Dec 2009 13:21:05 -0500
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Sent to CCL by: Geoffrey Hutchison [geoffh]=[pitt.edu]
> I will be pleased if you can point me to a (step by step) guide on how =
to build a polythiophene=20
> unit cell for a pbc gaussian calculation, using GaussView or any other =
program.
> Please note: I don=B4t need only the input file, I want to learn how =
to build the unit cell.
This was easy enough to do, I wrote a quick walkthrough using Avogadro.
http://avogadro.openmolecules.net/wiki/Tutorials:Polymer_Unit_Cell
It only takes a few minutes if you're willing to start from the =
MM-optimized geometry. To be more accurate, I'd start with a =
DFT-optimized oligomer and "chop out" a central pair of rings.
The main thing is that the Align tool in Avogadro allows you to put one =
atom at the origin and project another atom into a particular Cartesian =
axis. This is useful whenever you want to set a specific frame of =
reference for molecular coordinates.
Best regards,
-Geoff
---
Prof. Geoffrey Hutchison
Assistant Professor, Department of Chemistry
University of Pittsburgh
http://hutchison.chem.pitt.edu/
Office: (412) 648-0492
From owner-chemistry@ccl.net Sun Dec 6 18:12:01 2009
From: "Stephen Bowlus chezbowlus__comcast.net" <owner-chemistry[a]server.ccl.net>
To: CCL
Subject: CCL: van't Hoff factor
Message-Id: <-40872-091206175413-1606-3u75LiEG5MHT0i7ESU46DA[a]server.ccl.net>
X-Original-From: Stephen Bowlus <chezbowlus%x%comcast.net>
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Date: Sun, 6 Dec 2009 14:54:00 -0800
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Sent to CCL by: Stephen Bowlus [chezbowlus(!)comcast.net]
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Are there some simple, structural rules of thumb (a qualitative SAR,
if you will) that relate the van't Hoff factor to solution
concentration? At infinite dilution, _i_ = number of particles
possible from complete dissociation. From tables I have seen, it
seems though, that different ions (and ion combinations) have
different slopes in a plot of i vs [solute]. Is it possible to
predict that slope for an ion/ion pair?
Steve Bowlus
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<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Are there some simple, structural rules of thumb (a qualitative SAR, if you will) that relate the van't Hoff factor to solution concentration? At infinite dilution, <i>_</i>i<i>_</i> = number of particles possible from complete dissociation. From tables I have seen, it seems though, that different ions (and ion combinations) have different slopes in a plot of i vs [solute]. Is it possible to predict that slope for an ion/ion pair?<div><br></div><div>Steve Bowlus</div></body></html>
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