Kirk,
Your comment is correct with respect to construction of basis sets;
however in any of the ZDO schemes, or other more elegant schemes, the
choice of basis set, the choice of post-SCF treatment, or the choice of
a DFT functional [or its construction] to get results that best
reproduce experiment is routinely done and is either semi-empirical or
purely empirical. Which term suits the best, I do not know. IMHO,
"Everybody adjusts something to get the best answer."
Regards,
John McKelvey
On Dec 12, 2007 6:59 PM, Kirk Peterson kipeters-*-wsu.edu
<http://wsu.edu>;
<owner-chemistry],[ccl.net
<mailto:owner-chemistry],[ccl.net>> wrote:
Sent to CCL by: Kirk Peterson [kipeters-$-wsu.edu <http://wsu.edu>;]
As a sidebar to this discussion, I have to strongly disagree that
basis set parameters, exponents or contraction coefficients,
use empirical data in their construction. All commonly used basis
sets, even the Pople-style sets, are generated by optimizing
exponents and contraction coefficients to minimize (ab initio)
energies of atoms and sometimes molecules. Some of the Pople-style
basis sets utilize scale factors to apply to atom-optimized exponents,
but these were based on (ab initio) molecular calculations
and not experimental data.
regards,
-Kirk
On Dec 12, 2007, at 8:21 AM, Rene Fournier renef+*+yorku.ca wrote:
>
> Sent to CCL by: Rene Fournier [renef\a/yorku.ca]
> David Craig and Robert Parr first used "ab initio" in
quantum
> chemistry,
> see
> http://www.quantum-chemistry-history.com/Parr1.htm
> Near the middle of that page, Parr recounts:
>
> " Craig and I published this paper on "configuration
interaction in
> benzene", where we took the pi-system and did essentially a
complete
> configuration interaction calculation on it.
>
> That has some trivial historical interest in that it was there that
> the
> word, the term ab initio was introduced. Craig and Ross had computed
> everything from the start in London and I had personally computed
> everything from start in Pittsburgh. Then we compared our answers
> when we
> were finished- This involved computing of all the integrals as
best as
> they could be done and selecting the configurations to mix for the
> ground
> and exited states because there were electronic states that were of
> experimental interest and we checked our answers one against each
> other
> when we were finished. And what the paper says is, that these
> calculations
> were done ab initio by Craig and Ross and by me, independently. And
> Mulliken later said that this was the introduction of the term ab
> initio
> into quantum chemistry. In the short review that you have, I talk
> about
> this and reproduce a picture of a letter from Craig to me where he
> uses
> the term ab initio in a different context. So ab initio was
> introduced in
> the quantum chemistry by Craig in a letter to me and I put it
into the
> manuscript. That's where ab initio came from. "
>
>
> Funny thing is Parr later became a champion of Density Functional
> Theory
> and for many years (70's, 80's) DFT practitioners were often
> criticized
> for doing calculations that were not "ab initio". I think
views have
> changed now; "first-principles" was introduced probably to
say
> "mostly
> not empirical" but without the implications "ab initio"
had acquired
> over
> the years. The term "ab initio calculation", as it's
commonly used,
> very rarely refers to a calculation "devoid of empiricism",
for
> example
> the choice of basis set parameters is almost always empirical,
> see discussion on
>
http://www.ccl.net/chemistry/resources/messages/2001/11/28.002-dir/index.html
>
> Rene Fournier Office: 303 Petrie
> Chemistry Dpt, York University Phone: (416) 736 2100 Ext. 30687
> 4700 Keele Street, Toronto FAX: (416)-736-5936
> Ontario, CANADA M3J 1P3 e-mail: renef*_* yorku.ca
<http://yorku.ca>;
>
>
> On Wed, 12 Dec 2007, Christoph Etzlstorfer christoph.etzlstorfer .
> jku.at <http://jku.at>; wrote:
>
>> There is a story about that in Michael J.S. Dewars biography
"A
>> semiempirical life", American Chemical Society, 1992, p. 129.
>>
>> Best regards
>>
>> Christoph
>>
>>
>> Am 11.12.2007 um 03:13 schrieb Tommy Ohyun Kwon ohyun.kwon _
>> chemistry.gatech.edu <http://chemistry.gatech.edu>;:
>>
>>>
>>> Sent to CCL by: Tommy Ohyun Kwon [ohyun.kwon .
chemistry.gatech.edu <http://chemistry.gatech.edu>;]
>>> Dear CCLers;
>>> I would appreciate it if anyone could tell me who used the
term of
>>> "ab initio
>>> calculations" first.
>>> Thank you very much for your kind attention.
>>>
>>> Best wishes,
>>>
>>> Tommy
>>>
>>>
>>> --
>>> Tommy Ohyun Kwon, Ph.D
>>> School of Chemistry and Biochemistry
>>> Georgia Institute of Technology
>>> Atlanta Georgia, 30332
>>> Email: ohyun.kwon]*[chemistry.gatech.edu
<http://chemistry.gatech.edu>;
>>>
>>>
>>>
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>>
>> ####################################################
>> www.etzlstorfer.com
<http://www.etzlstorfer.com>;
>> ***********************************************************
>> Dr. Christoph Etzlstorfer Phone: *43-732-2468-8750
>> Universitaet Linz Fax: *43-732-2468-8747
>> A-4040 Linz E-mail: christoph.etzlstorfer,+,jku.at
<http://jku.at>;
>> Austria http://www.orc.uni-linz.ac.at
>> ####################################################
>>
>>
>>
>>
>>
>
>
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