From owner-chemistry@ccl.net Tue Oct 19 00:15:00 2010 From: "Narendra narendrax[*]gmail.com" To: CCL Subject: CCL: questions about how to optimize a large system efficiently Message-Id: <-42974-101019000947-5624-R0KHU4pzMwOlgk/OYlGfDA(!)server.ccl.net> X-Original-From: Narendra Content-Type: multipart/alternative; boundary=005045016da2c04c630492f07510 Date: Tue, 19 Oct 2010 09:39:11 +0530 MIME-Version: 1.0 Sent to CCL by: Narendra [narendrax===gmail.com] --005045016da2c04c630492f07510 Content-Type: text/plain; charset=ISO-8859-1 Hi Heng, in my opinion, it's quite ok to follow this method, as optimizing initially by small besis sets then going to larger set will surely save the computation time. But the things to remember in mind is.... if ur system has any structural specification which demands specific basic set...then u muct looking in to the guide lines of Go3. Regards Dr Narendra Revanuri On Mon, Oct 18, 2010 at 3:29 PM, Heng Zhang chemzhh(!)163.com < owner-chemistry]=[ccl.net> wrote: > > Sent to CCL by: "Heng Zhang" [chemzhh/a\163.com] > Dear All, > Now I am optimizing a large system. I have two questions as following: > 1 If I use small basis (such as 3-21g, etc.) to do the optimization first, > then use the optimized structure as the initial structure and do > optimization again with large basis (such as 6-31g, etc.). Is this is OK for > saving computation time? I am wandering whether the first optimization using > small basis would get wrong results and the initial structure from the first > optimization is not good for the second optimization. > 2 Which one is better as to the idea of whether optimizing real system > using small basis or optimizing simplified system (such as using PMe3 > instead of PPh3) using large basis? > > Thanks in advance > > Heng> > > --005045016da2c04c630492f07510 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable = Hi=A0Heng, = in my=A0opinion, it's quite ok to follow this method, as optimizing ini= tially by small besis sets then going to larger set will surely save the co= mputation time. But the things to remember in mind is.... if ur system has = any structural=A0specification which demands specific basic set...then u mu= ct looking in to the guide lines of Go3.
=
=

Regards=A0
<= div>
Dr Narendra Revanuri=A0<= /font>
=A0=A0=

On Mon, Oct = 18, 2010 at 3:29 PM, Heng Zhang chemzhh(!)163.co= m <owne= r-chemistry]=[ccl.net> wrote:

Sent to CCL by: "Heng =A0Zhang" [chemzhh/a\163.com]
Dear All,
Now I am optimizing a large system. I have two questions as following:
1 If I use small basis (such as 3-21g, etc.) to do the optimization first, = then use the optimized structure as the initial structure and do optimizati= on again with large basis (such as 6-31g, etc.). Is this is OK for saving c= omputation time? I am wandering whether the first optimization using small = basis would get wrong results and the initial structure from the first opti= mization is not good for the second optimization.
2 Which one is better as to the idea of whether optimizing real system usin= g small basis or optimizing simplified system (such as using PMe3 instead o= f PPh3) using large basis?

Thanks in advance

Heng



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--005045016da2c04c630492f07510-- From owner-chemistry@ccl.net Tue Oct 19 14:13:00 2010 From: "Shirin Seifert shirin.seifert%a%gmail.com" To: CCL Subject: CCL: RTT Message-Id: <-42975-101019141033-22762-M1MiMgXOKAYoHhZlu/pFeA+/-server.ccl.net> X-Original-From: Shirin Seifert Content-Type: multipart/alternative; boundary=0016e649c4be075ca40492fc352a Date: Tue, 19 Oct 2010 21:40:25 +0330 MIME-Version: 1.0 Sent to CCL by: Shirin Seifert [shirin.seifert|,|gmail.com] --0016e649c4be075ca40492fc352a Content-Type: text/plain; charset=ISO-8859-1 Hi, Could anyone please explain these to me in molecular systems and how to calculate them (how to estimate them roughly? any formulas?) 1- Reorganization Energy 2- Tunneling Barrier 3- Tunneling Energy Thank you in advance --0016e649c4be075ca40492fc352a Content-Type: text/html; charset=ISO-8859-1 Hi,
Could anyone please explain these to me in molecular systems and how to calculate them (how to estimate them roughly? any formulas?)
1- Reorganization Energy
2- Tunneling Barrier
3- Tunneling Energy

Thank you in advance
--0016e649c4be075ca40492fc352a--