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William David Thweatt
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 Posted: Thu Aug 07, 2003 4:45 pm Post subject: Re: Prediction of the outcomes of a reaction |
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Joćo Antonio (jas_bomfim@uol.com.br) wrote:
: I read Levine>s book for a physical chemistry course.
: And I do remember that many tricks were used to get
: solutions for equations which didn>t have *analytical*
: solutions. i.e., the results may be precise and acurate,
: but are not *the truth*...
The key is "exact." We can get the exact solution to the nonrelativistic
enegy of any hydrogen-like ion (i.e. one electron). Once you add another
electron, you need to start with the approximations.
The most common is the Linear Combination of Atomic Orbitals (LCAO)
approximation. This is a variational treatment using hydrogen-like
functions as basis functions. From there, you can do many things to
incorporate electron-electron interactions.
--
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William "Dave" Thweatt
Robert E. Welsh Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil |
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William David Thweatt
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| Posted: Thu Aug 07, 2003 4:46 pm Post subject: Re: Prediction of the outcomes of a reaction |
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David T. Croft (dtchlc@comcast.net) wrote:
: Intuition is knowing something without knowing why one knows it.
How did I know you were going to say that?
--
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William "Dave" Thweatt
Robert E. Welsh Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil |
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Joćo Antonio
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| Posted: Thu Aug 07, 2003 6:30 pm Post subject: Re: Prediction of the outcomes of a reaction |
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I read Levine>s book for a physical chemistry course.
And I do remember that many tricks were used to get
solutions for equations which didn>t have *analytical*
solutions. i.e., the results may be precise and acurate,
but are not *the truth*...
"William David Thweatt" <thweatt@rice.edu> escreveu na mensagem
news:bgrn8q$e19$12@joe.rice.edu...
[quote]Joćo Antonio (jas_bomfim@uol.com.br) wrote:
: I am not a computational chemistry expert, but I think that even ab
initio
: methods are aproximate. They don>t use any parameters, that>s right, but
: the maths are worked so you get things like 'self consistent fields' and
: 'minimise the gradient'.
Try getting ahold of a copy of Levine. The current edition is a must-read
for any chemist who wants to understand the power and limitations of
ab-initio quantum chemical calculations.
--
--
William "Dave" Thweatt
Robert E. Welsh Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil
[/quote]
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Joćo Antonio
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| Posted: Thu Aug 07, 2003 6:31 pm Post subject: Re: Prediction of the outcomes of a reaction |
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I think we agree (I meant "someone learns a knowledge" and not
"someone learns intuition"...)
"William David Thweatt" <thweatt@rice.edu> escreveu na mensagem
news:bgrn57$e19$11@joe.rice.edu...
[quote]Joćo Antonio (jas_bomfim@uol.com.br) wrote:
: > Someone mentioned chemical intuition. Some people develop a sense for
: > people. Some develop a sense for chemical reactions.
: Can we say that intuition is an inconscious knowledge one learns?
: This way, I totally agree.
I always have considered intuition to be the unconscious application of
previously compiled knowledge.
I hope that helps.
--
--
William "Dave" Thweatt
Robert E. Welsh Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil
[/quote]
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David T. Croft
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| Posted: Thu Aug 07, 2003 9:51 pm Post subject: Re: Prediction of the outcomes of a reaction |
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Intuition is knowing something without knowing why one knows it.
"Joćo Antonio" <jas_bomfim@uol.com.br> wrote in message
news:bgtk9q$ktc$1@news.mc.ntu.edu.tw...
[quote]I think we agree (I meant "someone learns a knowledge" and not
"someone learns intuition"...)
"William David Thweatt" <thweatt@rice.edu> escreveu na mensagem
news:bgrn57$e19$11@joe.rice.edu...
Joćo Antonio (jas_bomfim@uol.com.br) wrote:
: > Someone mentioned chemical intuition. Some people develop a sense
for
: > people. Some develop a sense for chemical reactions.
: Can we say that intuition is an inconscious knowledge one learns?
: This way, I totally agree.
I always have considered intuition to be the unconscious application of
previously compiled knowledge.
I hope that helps.
--
--
William "Dave" Thweatt
Robert E. Welsh Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil
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David T. Croft
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| Posted: Fri Aug 08, 2003 11:57 am Post subject: Re: Prediction of the outcomes of a reaction |
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It was intuition, I guess.
"William David Thweatt" <thweatt@rice.edu> wrote in message
news:bgtvos$a4e$35@joe.rice.edu...
[quote]David T. Croft (dtchlc@comcast.net) wrote:
: Intuition is knowing something without knowing why one knows it.
How did I know you were going to say that?
--
--
William "Dave" Thweatt
Robert E. Welsh Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil[/quote] |
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Joćo Antonio
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| Posted: Sat Aug 09, 2003 8:41 am Post subject: Re: Prediction of the outcomes of a reaction |
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[quote]The key is "exact." We can get the exact solution to the nonrelativistic
enegy of any hydrogen-like ion (i.e. one electron). Once you add another
electron, you need to start with the approximations.
[/quote]
That>s exactly what I was trying to say...
At least, in Portuguese "exact = accurate"
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William David Thweatt
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| Posted: Mon Aug 11, 2003 5:53 pm Post subject: Re: Prediction of the outcomes of a reaction |
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Joćo Antonio (jas_bomfim@uol.com.br) wrote:
: > The key is "exact." We can get the exact solution to the nonrelativistic
: > enegy of any hydrogen-like ion (i.e. one electron). Once you add another
: > electron, you need to start with the approximations.
: That>s exactly what I was trying to say...
: At least, in Portuguese "exact = accurate"
In English mathematical language, they are have two different meanings.
--
--
William "Dave" Thweatt
Robert E. Welsh Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil |
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