Subject: Re: CCL:Hydrogen-Bond in Gaussian

From: Kerwin D Dobbs <Kerwin.D.Dobbs %x% usa.dupont.com>
Date: Wed, 29 Jun 2005 13:15:37 -0400

For the hypothetical XH---YZ system in a Gaussian optimization, if the H 
does indeed ultimately bond to Y, then you truly did not have a 
hydrogen-bonded system in the first place. The reverse situation is true 
as well.

Kerwin 

Pradyumna Shaakuntal Singh <pradyumna.singh %x% gmail.com> 
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06/29/05 05:35 AM
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Subject
CCL:Hydrogen-Bond in Gaussian

Hello,

I'm trying to study the energetics of proton transfer in hydrogen-bonded 
systems using ab initio methods. 
For any H-bond pair X-H -----Y-Z  (where the proton on X-H is 
hydrogen-bonded to Y on Y-Z), when I do an optimization of the structure, 
is there a way in Gaussian, by which I can ensure that the proton stays 
explicitly bonded to X, so that it doesnt travel too far afield and bond 
to Y.

Further, if I do want the proton to bond to Y but remain H-bonded to X- 
(-X ------ H-Y-Z), how can I optimize this configuration.

Essentially, I wish to have some control over where the proton is (without 
really freezing the proton coordinate entirely), and then perform the 
optimizations. Any suggestions are appreciated.

Thanks,
Pradyumna

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---

From: errol lewars <elewars #%# trentu.ca>
Date: Wed, 29 Jun 2005 12:44:00 -0400

2005 June 29

Hello,

Can't you use the constraints or freeze option in Gaussian (see the 
manual) to fix the X-H and/or H-Y distance while the other geometric 
parameters are optimized?
There is also the possibility of a scan, in which one or two distances 
are varied, giving a table from which a 2D or 3D potential energy 
(energy vs. geometry; constrained or relaxed) surface can be plotted.

EL
====================

Pradyumna Shaakuntal Singh wrote:

> Hello,
>
> I'm trying to study the energetics of proton transfer in 
> hydrogen-bonded systems using ab initio methods.
> hydrogen-bonded to Y on Y-Z), when I do an optimization of the 
> structure, is there a way in Gaussian, by which I can ensure that the 
> proton stays explicitly bonded to X, so that it doesnt travel too far 
> afield and bond to Y.
>
> Further, if I do want the proton to bond to Y but remain H-bonded to 
> X-  (-X ------ H-Y-Z), how can I optimize this configuration.
>
> Essentially, I wish to have some control over where the proton is 
> (without really freezing the proton coordinate entirely), and then 
> perform the optimizations. Any suggestions are appreciated.
>
> Thanks,
> Pradyumna

---

From: Laurence Cuffe <Laurence.Cuffe :a: ucd.ie>
Date: Wed, 29 Jun 2005 21:49:43 +0100

----- Original Message -----
From: Pradyumna Shaakuntal Singh <pradyumna.singh :a: gmail.com>
Date: Wednesday, June 29, 2005 10:35 am
Subject: CCL:Hydrogen-Bond in Gaussian

> Hello,
Hmm. I wonder would it be interesting to perform a relaxed potential 
energy scan where
what was being varied was the distance X-H. As you move H further from 
X you will probably see Y come closer and perhaps bond to H.  
All the best, 
Dr Laurence Cuffe
> hydrogen-bonded 
> to Y on Y-Z), when I do an optimization of the structure, is there 
> a way in 
> Gaussian, by which I can ensure that the proton stays explicitly 
> bonded to 
> X, so that it doesnt travel too far afield and bond to Y.
> 
> Further, if I do want the proton to bond to Y but remain H-bonded 
> to X- (-X 
> ------ H-Y-Z), how can I optimize this configuration.
> 
> (without