From chemistry-request(+ at +)ccl.net Thu Nov 11 07:37:19 2004 Received: from celebris04.cetem.gov.br (correio.cetem.gov.br [200.20.105.10]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id iABCbEX4007539 for ; Thu, 11 Nov 2004 07:37:15 -0500 Received: by correio.cetem.gov.br with Internet Mail Service (5.5.2655.55) id ; Thu, 11 Nov 2004 10:49:31 -0300 Message-ID: <4DB0991764FED5119A2A000475B057CA1C5898|at|correio.cetem.gov.br> From: Ian Hovell To: "'chemistry'" Subject: CCL: Summary: Integration grid defaulting to unpruned value Date: Thu, 11 Nov 2004 10:49:22 -0300 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2655.55) Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C4C7F5.3F9A0570" X-Spam-Status: No, hits=2.0 required=7.5 tests=HTML_FONTCOLOR_UNKNOWN, HTML_MESSAGE,LINES_OF_YELLING autolearn=no version=2.61 X-Spam-Checker-Version: SpamAssassin 2.61 (1.212.2.1-2003-12-09-exp) on servernd.ccl.net This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C4C7F5.3F9A0570 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Many thanks. My original question was =20 I am calculating the heats of reactions containing organo-mercury = compounds. I am using G03 and DFT methods. The program, when mercury is involved, defaults to an unpruned integration grid for this atom. The manual = states that one should use the same grid when comparing energies. Does this = mean that I should be defining an unpruned grid for all of my calculations = i.e. the compounds without mercury in the isodesmic reaction? If so how do I define an unpruned grid the same as the one being used by gaussian when mercury is involved. The manual does not talk about unpruned grids. I = have enclosed the relevant output section below.=20 And the replies:- =20 Only the mercury atom will use the unpruned grid. All the other atoms will use the default, pruned grid if it is defined. =20 So you need not do anything special in generating the pieces of the reaction. Each element will be done the same way if you use the defaults in Gaussian. =20 The point of printing the informational message is in the event that you compare with another program or a future release of Gaussian were a pruned grid for mercury might be used. Douglas J. Fox Technical Support Gaussian, Inc. =20 fox|at|gaussian.com =20 =20 I think the manual is referring to using different grid densities, that is, INT=3DULTRAFINE versus INT=3DFINE. A pruned grid has some of the = points removed (hence the word 'pruned') so it is faster, but it should give the same result as an unpruned grid, for the same integration grid density. =20 To summarise, I think you don't need to worry about the pruned grid, so long as you use the same integration grid density (for example, the default integration grid density) for all calculations. =20 Regards, Noel =20 =20 Ian Hovell - Ph.D.=20 NUCLEO DE MODELAGEM MOLECULAR-NMM=20 Centro de Tecnologia Mineral - CETEM=20 Ministerio da Ci=EAncia e da Tecnologia- MCT=20 Avenida Ip=EA, No 900 - Cidade Universitaria=20 Ilha do Fund=E3o Rio de Janeiro RJ Brasil=20 CEP 21941-590=20 tel 00 55 (xx) 3865 7344 ou 3865 - 7216=20 Fax 00 55 (xx) 22602837 ou 2290-4286=20 e-mail hovell|at|cetem.gov.br =20 ------_=_NextPart_001_01C4C7F5.3F9A0570 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Many thanks.

My original question was

=

I am calculating the heats of reactions = containing organo-mercury compounds. I am using G03 and DFT methods. The program, = when mercury is involved, defaults to an unpruned integration grid for this = atom. The manual states that one should use the same grid when comparing = energies. Does this mean that I should be defining an unpruned grid for all of my calculations i.e. the compounds without mercury in the isodesmic = reaction? If so how do I define an unpruned grid the same as the one being used by = gaussian when mercury is involved. The manual does not talk about unpruned = grids. I have enclosed the relevant output section below. =

And the replies:-

=

Only the mercury atom = will use the unpruned grid. All = the other

atoms = will use the default, pruned grid if it is defined.

So you need not do = anything special in generating the pieces of

the reaction. Each element = will be done the same way if you use

the = defaults in Gaussian.

The point of printing = the informational message is in the event that

you = compare with another program or a future release of Gaussian were

a pruned = grid for mercury might be used.

Douglas = J. Fox

Technical Support

Gaussian, = Inc.

fox|at|gaussian.com=

I think = the manual is referring to using different grid densities, = that

is, INT=3DULTRAFINE versus INT=3DFINE. A pruned grid has some of the = points

removed = (hence the word 'pruned') so it is faster, but it should = give

the same = result as an unpruned grid, for the same integration grid

density.

To = summarise, I think you don't need to worry about the pruned grid, = so

long as = you use the same integration grid density (for example, the

default integration grid density) for all calculations.

Regards,=

Noel

=

=

<= font color=3Dblack>Ian = Hovell - Ph.D.

NUCLEO = DE MODELAGEM MOLECULAR-NMM

Centro de Tecnologia Mineral - CETEM

Ministerio da Ci=EAncia e da Tecnologia- MCT

Avenida Ip=EA, No 900 - Cidade Universitaria

Ilha do Fund=E3o Rio de Janeiro RJ Brasil

CEP 21941-590

tel 00 55 (xx) 3865 7344 ou 3865 - 7216

Fax 00 55 (xx) 22602837 ou 2290-4286 <= o:p>

e-mail hovell|at|cetem.gov.br

=

------_=_NextPart_001_01C4C7F5.3F9A0570--