Subject: summary: Computational Chemistry vs Theoretical

From: Tek <[email-masked]>
Date: Wed, 7 Apr 1999 18:48:27 -0400 (EDT)

Hi all!

Thanks to all those who have contributed.

Here is a summary of all the responses.

Stephen Kim
Department of Chemistry
Queen's University
Kingston, Ontario
K7L-3N6
--------------------------------------------------------------------------

From: Rene Fournier <[email-masked]>
To: STK <[email-masked]>
Cc: [email-masked]
Subject: Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
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Hello,

   There is no universally accepted answer to that question, but
it's a very interesting question.  There was a debate about 2 years
ago on the CCL on the difference between "computational chemistry"
and "molecular modeling" and it went into "theoretical chemistry"
also.  I collected some opinions voiced on CCL, edited them, and
wrote a short essay in an effort to organize my own thoughts on that.
If you're interested it's on my web page:

http://www.science.yorku.ca/chem/profs/renef/whatiscc.html#descriptioncc

   In short, my definition would be:

- a computational chemist is someone who turns theories into numbers
  (and usually explains, or compares to, experiments); or someone who
  devises approximations or better algorithms or better programs to
  make calculations faster.

- a theoretical chemist is someone who makes new theories: there are
  very, very few persons in that category in my view.

   A good test of "computation" vs "theory" is to imagine what would
happen if we suddenly had INFINITELY fast and powerful computers (the
starting point of a discussion in Physics Today some time back).  If
we had INFINITELY fast and powerful computers that were extremely easy
to use, computational chemistry would quickly disappear.  There would
be no need at all for expert computational chemists; just click on
the option "full CI, complete basis set, molecular dynamics with
10**50 time steps, with explicit treatment of solvent and  impurities,
etc..." and you instantly get all properties you want from the computer,
with as much accuracy as you want.  But there would still be a need for
theoretical chemists.
   Maybe a more practical test of "computation" vs "theory" could
be this: the work of a theoretical chemist would not be affected much
by having exclusive access to a 256-node super-computer instead of an
old standalone PC; but the work of a computational chemist would be very
much affected by that.

-- Rene Fournier.

 --------------------------------------------------------------------
 | Rene Fournier                  | Bureau/Office  303 Petrie       |
 | Chemistry Dpt, York University |      (416) 736 2100 Ext. 30687  |
 | 4700 Keele Street,  Toronto    | FAX: (416) 736-5936             |
 | Ontario, CANADA   M3J 1P3      | e-mail: [email-masked]          |
 --------------------------------------------------------------------

Date: Fri, 26 Mar 1999 09:43:43 +36000
From: Richard Wood <[email-masked]>
To: STK <[email-masked]>
Cc: [email-masked]
Subject: Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
In-Reply-To: <[email-masked]>
Message-Id: <[email-masked]>
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Hi-
   I would say that theoretical chemistry involves either a) developing 
theories, or b) using theories that involve quantum chemistry.  I would 
say that computational chemistry is the use of tools, be they quantum 
mechanical, or, mostly semi-empirical.  Thus, IMO, computational 
chemistry is a sub-field of theoretical chemistry.  
   In my "work" as a Ph. D. candidate, I do MD simulations of 
biologically important molecules.  These simulations involve classical 
mechanics and other semi-empirical techniques.  When people ask what I 
do, I say "I am a computational chemist", because i don't develop theory, 
I just use what theory has already been developed by others.

Richard

From: [email-masked] (Georg Schreckenbach)
Subject: Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
Status: RO
X-Status: 

Hi Stephen,

unfortunately, I don't have any "authorative" comments. However, I'd like
to point out that you can clearly do "theoretical chemistry" with just
paper and pencil, i.e., without a computer. In that sense, "theoretical
chemistry" would be the more general descriptor of the two, and it would
comprise "computational chemistry" as a sub-area. Btw., I view myself as a
"theoretical" AND a "computational" chemist ...

Best regards, Georg

P.S. please summarize ...

--
==============================================================
Dr. Georg Schreckenbach           Tel:     (USA)-505-667 7605
Theoretical Chemistry T-12        FAX:     (USA)-505-665 3909
M.S. B268, Los Alamos National      E-mail:  [email-masked]
Laboratory, Los Alamos, New Mexico, 87545, USA
Internet:    http://www.t12.lanl.gov/home/schrecke/  ***new location!***
==============================================================

From: "Preston J. MacDougall" <[email-masked]>
Subject: Re: Computational Chemist vs Theoretical Chemist
In-Reply-To: <[email-masked]>
X-Sender: [email-masked]
To: STK <[email-masked]>
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Hello Stephen,
   I am sure that there is no consensus on what differentiates a
computational chemist from a theoretical one.  I am equally sure that many
chemists wear both of these hats.  I would suggest that computational
chemistry is to theoretical chemistry what synthesis is to analysis in
other branches of chemistry.  Computational chemistry involves applied
mathematics, computer programming and lots of number crunching to
"construct" wavefunctions, potential energy surfaces et cetera, whereas
theoretical chemistry involves much of the same "apparatus" but the goal is
to provide answers to questions couched in the language of chemistry,
usually extracted fromthe fruits of computational chemistry but sometimes
with paper and pencil!
   Queen's own Vedene Smith is an example of a theoretical chemist of the
finest calibre.  Please say hello to him for me!  Is Minhhuy Ho still
there?  If so please say "Hi" to him as well.  Hartmut? ditto!

Please summarize.  I am sure many people are curious to see what other
people say about this "word problem".

Best wishes from Middle Tennessee,

Preston J. MacDougall
Assistant Professor
Department of Chemistry, Box X101
Middle Tennessee State University
Murfreesboro, TN 37132

http://www.mtsu.edu/~chem/

Date: Fri, 26 Mar 1999 15:29:29 +0100 (CET)
From: Stefan Konietzny <[email-masked]>
To: STK <[email-masked]>
Cc: [email-masked]
Subject: Re: Computational Chemist vs Theoretical Chemist
In-Reply-To: <[email-masked]>
Message-Id: <[email-masked]>
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Hello everybody,

If you take this question serious for yourself, stop reading and delete
the message NOW.

we are using a computer to do theoretical chemistry. I think there was a
time when people did theoretical chemistry without a computer. They were
theoretical chemists but not computational chemists.
So what about Computational Theoretical Chemist. But Computation
implements that it is theoretical; no?
Or is it only theoretical, when it is really theoretical, i mean when you
calculate things that man has never seen before. 
We can use the term Applied Theoretical Chemist, for those who calculate
things the Lab-Chemist (or is it a Synthetical Chemist?) has synthesized.
But there is organic, inorganic, physical...
Oh my good, in the end its Physical Chemistry!
I think i am falling more and more into an identity crisis. I am
calculating (we are all calculators!) inorganic molecules (although there 
is carbon in it, they are inorganic).
Until i know who or what i am, i call myself:

Molecular Modeller in Applied Theoretical Inorganic Computational Quantum
Chemistry.  

:-)

Stefan.

!!!!!    reply to: [email-masked]     !!!!!
finger or talk request: [email-masked]
****************************************************************
*                      Stefan Konietzny                        *
*--------------------------------------------------------------* 
*Fachbereich Chemie, AK Frank  |  Dept. of Chemistry           *
*Universitaet Kaiserslautern   |  University of Kaiserslautern *
*Erwin-Schroedingerstr.        |  Erwin-Schroedingerstr.       *
*67663 Kaiserslautern          |  D-67663 Kaiserslautern       *
*0631/205-2964                 |  +49-631/205-2964             *
****************************************************************

From: Jose Luis Carreon Macedo <[email-masked]>
To: STK <[email-masked]>
Subject: Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
In-Reply-To: <[email-masked]>
Message-Id: <[email-masked]>
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Status: RO
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Hi!
I had the same question and I found useful the next FAQ of
Dr. Alan Shusterman. 
http://www.reed.edu/~alan/324/faq.html
I hope this help you.

--------------)(---------------
Jose Luis Carreon Macedo
Mexico UNAM Facultad de Quimica
Fisica y Quimica Teorica DEPg
[email-masked]

From: Brian Salter-Duke <[email-masked]>
To: STK <[email-masked]>
Subject: Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
References: <[email-masked]>
Mime-Version: 1.0
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In-Reply-To: <[email-masked]>; from STK on Thu, Mar 25, 1999 at 04:43:04PM -0500
Status: RO
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I'm both. When I am devising or improving methods I'm a theoretical 
chemist. When I am using the methods I am a computational chemist.

Also computational chemistry sounds more sexy than theoretical
chemistry so it being more widely used.

Cheers, Brian.
-- 
        Associate Professor Brian Salter-Duke (Brian Duke)
School of Mathematical and Physical Sciences, Northern Territory University,
          Darwin, NT 0909, Australia.  Phone (61) (0)8-89466702
e-mail: [email-masked]  or [email-masked]

Date: Mon, 29 Mar 1999 11:41:29 -0500 (EST)
From: "Prof. Robert Topper" <[email-masked]>
X-Mailer: ELM [version 2.4 PL23]
Sender: Computational Chemistry List <[email-masked]>
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Hello all

I think Stefan's got it just right (especially about the need
to have a sense of humor!). 

I was trained as a theoretical chemist. To me, what this means
is that I was trained to push a pencil with the goal of developing
certain mathematical aspects of chemistry. This includes making
theoretical improvements to transition-state theory, developing
new quantum path-integral representations, inventing a new theory
of the liquid state, working out better ways to set up
the integrals for 5th-order perturbation theory, and so forth.

Of course, I eventually use computers to implement all of the above.
But experimentalists use computers too. IMHO, 
this may also justifiably be called "computational chemistry"
(I know, not everyone agrees, this is an old debate, just my $0.02,
sincere apologies to all who find my heresy distasteful).

Novices tend to divide science into theory and
experiment, and therefore "computation must be theory."
As Stefan mentions, this is a historical bias.
Although computer simulation work is not experiment,
it isn't exactly theory either. When I was a student we used to
call computer simulations "numerical experiments" (these
days, maybe "virtual experiments" would be trendier), which
could be tested either against theory or experiment.

In Einstein's day things were different, but science now consists of
theory, experiment and simulation. Some people work in one, two or
even all three of these areas (I myself get into the lab once in
a blue moon).

So am I a theoretical physical chemist? A computational chemist?
A chemical physicist? A computational molecular thermodynamicist? 
Personally, I don't think of myself as any of the above.
I'm a chemist. 

*****************************************************************************
Robert Q. Topper                        email:   [email-masked]
Department of Chemistry                 phone:   (212) 353-4378
School of Engineering                   fax:     (212) 353-4341
The Cooper Union                        subway:  take the 6 to Astor Place
51 Astor Place                                   or the N/R to 8th street
New York, NY 10003                               and you're there!
*****************************************************************************
                 http://www.cooper.edu/engineering/chemechem/
*****************************************************************************

From: Stefan Konietzny <[email-masked]>
To: [email-masked]
Subject: CCL:Re: Computational Chemist vs Theoretical Chemist
Sender: [email-masked]
Errors-To: [email-masked]
Precedence: bulk
Status: RO
X-Status: 

Hello everybody,

If you take this question serious for yourself, stop reading and delete
the message NOW.

we are using a computer to do theoretical chemistry. I think there was a
time when people did theoretical chemistry without a computer. They were
theoretical chemists but not computational chemists.
So what about Computational Theoretical Chemist. But Computation
implements that it is theoretical; no?
Or is it only theoretical, when it is really theoretical, i mean when you
calculate things that man has never seen before. 
We can use the term Applied Theoretical Chemist, for those who calculate
things the Lab-Chemist (or is it a Synthetical Chemist?) has synthesized.
But there is organic, inorganic, physical...
Oh my good, in the end its Physical Chemistry!
I think i am falling more and more into an identity crisis. I am
calculating (we are all calculators!) inorganic molecules (although there 
is carbon in it, they are inorganic).
Until i know who or what i am, i call myself:

Molecular Modeller in Applied Theoretical Inorganic Computational Quantum
Chemistry.  

:-)

Stefan.

!!!!!    reply to: [email-masked]     !!!!!
finger or talk request: [email-masked]
****************************************************************
*                      Stefan Konietzny                        *
*--------------------------------------------------------------* 
*Fachbereich Chemie, AK Frank  |  Dept. of Chemistry           *
*Universitaet Kaiserslautern   |  University of Kaiserslautern *
*Erwin-Schroedingerstr.        |  Erwin-Schroedingerstr.       *
*67663 Kaiserslautern          |  D-67663 Kaiserslautern       *
*0631/205-2964                 |  +49-631/205-2964             *
****************************************************************

Date: Fri, 26 Mar 1999 09:43:43 +36000
From: Richard Wood <[email-masked]>
To: [email-masked]
Subject: CCL:Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
Sender: [email-masked]
Errors-To: [email-masked]
Precedence: bulk
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Hi-
   I would say that theoretical chemistry involves either a) developing 
theories, or b) using theories that involve quantum chemistry.  I would 
say that computational chemistry is the use of tools, be they quantum 
mechanical, or, mostly semi-empirical.  Thus, IMO, computational 
chemistry is a sub-field of theoretical chemistry.  
   In my "work" as a Ph. D. candidate, I do MD simulations of 
biologically important molecules.  These simulations involve classical 
mechanics and other semi-empirical techniques.  When people ask what I 
do, I say "I am a computational chemist", because i don't develop theory, 
I just use what theory has already been developed by others.

Richard

Date: Mon, 29 Mar 1999 09:43:15 +1000
To: STK <[email-masked]>
From: "Kieran F Lim (Lim Pak Kwan)" <[email-masked]>
Subject: Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
Status: RO
X-Status: 

A theoretical chemist works with theory -- devleoping theory,
writing equations, developing new models etc.
often, computation is required to prove/apply the theory.
quite often theory itself is the thing being tested.

A theoretical paper will have a section entitled "theory" which
is new theory. (cf. a synthetic paper reports a new synthesis.)

A computational chemist uses theoretical methods
to compute/calculate something. the theory itself is usually
not the thing being tested.

My own test is
a) if the user doing the calculation has
   in some way "value-added" to the calculation then that is
   theoretical chemistry.
b) on the other hand, if the user is
   just using a "black box" to do a calculation, then that is
   computational chemistry.

Kieran
------------------------------------------------------------
 Dr Kieran F Lim             Biol. and Chemical Sciences
 (Lim Pak Kwan)              Deakin University
 ph:  + [61] (3) 5227-2146   Geelong          VIC   3217
 fax: + [61] (3) 5227-1040   AUSTRALIA
 mailto:[email-masked]    http://www.deakin.edu.au/~lim  

Dear Stephen,

there is no "hard" line between the two, but in general, a theoretical
chemist is concerned more with the "pure theory" and the mathematical side of
quantum chemistry to develop new or revise existing approaches to
solving the Schroedinger equation; the focus sometimes is the 
computational implementation, i.e., the algorithms and programs.

A computational chemist, on the other hand, mostly uses the codes provided
by theoreticians to study chemical problems, with a strong
emphasis on the chemical interpretation and not so much on the underlying
theory.

Does this help?
Peter 

    ////
___|--00___________________________________________________________________
   C   ^    Dr. Peter R. Schreiner, Ph.D. (Univ. Georgia)  
    \ ~/    Institut fuer Organische Chemie     http://www.gwdg.de/~pschrei
    <><>    Georg-August Universitaet Goettingen
            Tammannstr. 2                          Phone: +49-(0)551-393287
            D-37077 Goettingen, Germany            FAX:   +49-(0)551-399475
___________________________________________________________________________

From: "Helder Marques" <[email-masked]>
Organization: CHEMISTRY -  WITS UNIVERSITY
To: STK <[email-masked]>
Date: Fri, 26 Mar 1999 11:46:54 GMT + 2:00
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Subject: Re: CCL:CCL: Computational Chemist vs Theoretical Chemist
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This is a personal opinion and not to be confused with any 
authoritative definition, but I would ahve thought a theoretical 
chemist was one concerned with a theoretical description of some 
aspect of chemistry whereas a computational chemist is one who 
would use computational procedures - perhaps well-established - 
as a *tool* to answer specific questions.  Hence the developers of 
MOPAC might consider themselves theoretical chemists, but 
users of the toolbox would be computational chemists - or is that 
too simplistic?

Helder
____________________________________________________________________

 Prof. Helder M. Marques
 Room C301, Department of Chemistry,
 University of the Witwatersrand, 
 P.O. Wits, Johannesburg,
 South Africa, 2050
 Fax: +27+11+339-7967; Tel: +27+11+716-2303
 http://www.chem.wits.ac.za

Date: Mon, 29 Mar 1999 14:46:30 +36000
From: Richard Wood <[email-masked]>
To: "Prof. Robert Topper" <[email-masked]>
Cc: [email-masked]
Subject: CCL:Computational Chemist vs Theoretical Chemist
In-Reply-To: <[email-masked]>
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Dr. Topper-
    While I agree with you when you say "I am a chemist", as I have 
several years of experience working in the IR/CD area, as well as three 
plus years of experience doing MD simulations, I must disagree with you 
when you imply that the distinction between being a "theoretical chemist" 
vs. a "computational chemist" doesn't matter.  It matters to me (however, 
don't think that I lose sleep over it) because to me developing a theory 
and using it are two ENTIRELY different things.  I think that most any 
chemist can USE a theory; only a special "bird" can develop theory.  

    Let me give you an example.  A few years back, I was measuring IR/CD 
spectra of some (chiral) tetrasubstituted biphenyls, and also attempting to 
calculate the observed IR/CD spectra by varying the angle between the two 
rings (in other words, trying to find the angle that gave me the closest 
match with my experimental results).  We were using a simple coupled 
oscillator model to calculate the spectra, and my calculations of the 
spectra were too small, regardless of what angle I picked.  I then came 
to the conclusion that the distance between the too dipoles was too 
small, and thus R+ and R- were cancelling out, decreasing their 
magnitude.  I also concluded that my theory needed some modification.  
Lacking the necessary theoretical "ability", my project basically crashed 
and burned.  I guess that you are probably aware being a physical 
chemist, that if you are going to try and publish experimental results, 
you better have very good agreement between experiment and calculations.

Richard

On Mon, 29 Mar 1999, Prof. Robert Topper wrote:

Date: 29 Mar 1999 16:59:58 -0500
From: "Boyd" <[email-masked]>
Return-Receipt-To: "Boyd" <[email-masked]>
Subject: definitions
To: "Kim, Stephen T." <[email-masked]>
X-Mailer: Mail*Link SMTP for Quarterdeck Mail; Version 4.1.0
Status: RO
X-Status: 

Hi Stephen,

On Friday you asked about the distinction between a computational chemist and
a theoretical chemist.  There is a third term also: molecular modeler.  You
have probably gotten a lot of opinions.  Here are mine.

The term theoretical chemist is the oldest term, and many academic quantum
chemists are quite happy to call themselves theoretical chemist.  This term is
fine for academics, but few companies want to hire a "theoretical" person. 
Therefore most people in industry call themselves computational chemist. They
do a lot of work in addition to just quantum chemistry.  Organic chemists
mainly interested in manipulating 3D structures of molecules call the
computational chemists "molecular modelers".  However, the term computational
chemist is a more general term, and encompasses a lot of computed-based
approaches, such as QSAR and bioinformatics, as you mention.

These terms have been discussed in the book series I edit.  For instance, take
a look at the Preface of Vol. 1, Reviews in Computational Chemistry (1990). 
Your university library should have it.

Let me know if you need further clarification.

Sincerely,
Don
Donald B. Boyd, Ph.D.
Editor, Reviews in Computational Chemistry
Editor, Journal of Molecular Graphics and Modelling
Research Professor of Chemistry
Department of Chemistry
Indiana University-Purdue University at Indianapolis
402 North Blackford Street
Indianapolis, Indiana 46202-3274, U.S.A.
Telephone 317-274-6891, FAX 317-274-4701
E-mail [email-masked]
Web http://chem.iupui.edu/rcc/rcc.html

Date: Mon, 29 Mar 1999 18:16:32 -0500 (EST)
From: "Prof. Robert Topper" <[email-masked]>
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Hi again all,

Sorry for the bandwidth. Just want to point out that I personally
feel that there is a very big difference between theoretical
chemistry and computational chemistry, and that was in fact what
I was trying to say - perhaps too obliquely.

My parting comment was merely put in to point out that I have no
particular axe to grind on this issue, as I have done work in
all three areas (although I have done most of my work
in the "theoretical" and "simulation" ends of things).
Any inferences of other, guessed-at meanings are simply incorrect.

Best, Robert

*****************************************************************************
Robert Q. Topper                        email:   [email-masked]
Department of Chemistry                 phone:   (212) 353-4378
School of Engineering                   fax:     (212) 353-4341
The Cooper Union                        subway:  take the 6 to Astor Place
51 Astor Place                                   or the N/R to 8th street
New York, NY 10003                               and you're there!
*****************************************************************************
                 http://www.cooper.edu/engineering/chemechem/
*****************************************************************************

> 
> Dr. Topper-
>     While I agree with you when you say "I am a chemist", as I have 
> several years of experience working in the IR/CD area, as well as three 
> plus years of experience doing MD simulations, I must disagree with you 
> when you imply that the distinction between being a "theoretical chemist" 
> vs. a "computational chemist" doesn't matter.  It matters to me (however, 
> don't think that I lose sleep over it) because to me developing a theory 
> and using it are two ENTIRELY different things.  I think that most any 
> chemist can USE a theory; only a special "bird" can develop theory.  
> 
>     Let me give you an example.  A few years back, I was measuring IR/CD 
> spectra of some (chiral) tetrasubstituted biphenyls, and also attempting to 
> calculate the observed IR/CD spectra by varying the angle between the two 
> rings (in other words, trying to find the angle that gave me the closest 
> match with my experimental results).  We were using a simple coupled 
> oscillator model to calculate the spectra, and my calculations of the 
> spectra were too small, regardless of what angle I picked.  I then came 
> to the conclusion that the distance between the too dipoles was too 
> small, and thus R+ and R- were cancelling out, decreasing their 
> magnitude.  I also concluded that my theory needed some modification.  
> Lacking the necessary theoretical "ability", my project basically crashed 
> and burned.  I guess that you are probably aware being a physical 
> chemist, that if you are going to try and publish experimental results, 
> you better have very good agreement between experiment and calculations.
> 
> Richard