On Fri, Apr 8, 2011 at 9:54 AM, Dr. Xiaofeng= (Frank) Duan duanx.ctr#afrl.hpc.mil <owner-chemis= try{:}ccl.net> wrote:

Sent to CCL by: "Dr. Xiaofeng (Frank) Duan" [duanx.ctr,+,afrl.hpc.mil]
Huub and Phil,

It's good to know about the "cold smearing" schemes. THANKS!<= br>
=A0>>all you need are E and E-TS and you can correct it yourself
As Huub noticed too, the T*S term is zero in all my cases with NWChem.
Looks like I have to re-run all the calculations.

Frank

On 04/07/11 18:36, Van Dam, Hubertus J HubertusJJ.vanDam!^!pnl.gov wrote:

Sent to CCL by: "Van Dam, Hubertus J" [HubertusJJ.vanDam{}pnl.gov]
Hi Frank,

I agree with you on the spin state. The S2 value does not seem to be affect= ed much by the smearing so that is probably OK. The units of the eFermi ene= rgy are indeed Hartrees (i.e. atomic units).

With respect to rerunning any calculations did you also see Phil Hasnip'= ;s comments on "cold smearing" total energy estimates (Phil thank= s for those). You might be able to use those to estimate the zero temperatu= re total energies (rather than rerunning your single point energies). If yo= u have missed Phil's message then please ping me directly and I will fo= rward the message to you. The one thing that does worry me is that the ener= gy of the calculations with smearing come out higher than the ones without.= At present I don't understand why that happens which makes me feel une= asy about this (which is why I am not sure about rerunning calculations eit= her). However, I have received a test case from Adam Pelzer (thanks for pro= viding that Adam) which I am running at the moment and I hope to have a han= dle on this soon.

As far as the zero-point corrections are concerned I simply don't know = how much of a difference that will make. If the temperature is small you wo= uld think it should not make a big difference but I don't know. So I wo= uld recommend just trying it out on a single molecule and see what you find= .

Best wishes,

=A0 =A0 Huub

-----Original Message-----

> From: owner-chemistry+hubertus.vandam=3D=3Dpnl.gov_+_ccl.net [mailto:owner-chemistry+hubertus.vandam= =3D=3Dpnl.gov_+_ccl.net] O= n Behalf Of Dr. Xiaofeng (Frank) Duan duanx.ctr++afrl.hpc.mil

Sent: Thursday, April 07, 2011 7:42 AM
To: Van Dam, Hubertus J
Subject: CCL: FW: smearing with NWChem

Sent to CCL by: "Dr. Xiaofeng (Frank) Duan" [duanx.ctr+*+afrl.hpc.mil]
Hi Huub and Niri,

Thanks much for your comments and suggestions.

In my case, I did see the energy increase with smearing and did not see
much spin state change. Take one case as example:

1. With default smear value (0.001):

....
sigma=3D .10D-02 eFermi=3D -0.31098 T*S=3D =A00.00E+00 nel(1)=3D =A0 53.00 = nel(2)=3D
=A0 52.00
....
Total DFT energy =3D =A0 =A0 -756.386904455476
....
<S2> =A0=3D =A0 =A0 =A00.7658 (Exact =3D =A0 =A0 0.7500)

2. Without smear:

Total DFT energy =3D =A0 =A0 -756.388015008368
.....
<S2> =A0=3D =A0 =A0 =A00.7666 (Exact =3D =A0 =A0 0.7500)

In above 1, is eFermi=3D -0.31098 the correction to the total energy in
unit au?

Anyway, I will take your suggestions to re-run single point calculations with the largest smear value and multiplicity preservation for all the
structures.
One more question, I also did vibrational frequencies to get thermal
corrections. Do you think I need re-do frequencies with the same smear
value to get consistent results, or it is OK to keep these thermal
corrections?

Thanks,
Frank

On 04/06/11 19:32, Van Dam, Hubertus J HubertusJJ.vanDam.[].pnl.gov wrote:

Sent to CCL by: "Van Dam, Hubertus J" [HubertusJJ.vanDam[-]pnl.gov]
Hi Frank,

In addition to my earlier post I am forwarding some additional comments fro= m Niri Govind. Please have a look below.

Best wishes,

=A0 =A0 =A0Huub

-----Original Message-----

> From: Govind, Niri

Sent: Wednesday, April 06, 2011 4:25 PM
To: Van Dam, Hubertus J; CCL Subscribers
Cc: nwchem-users^emsl.pnl= .gov
Subject: RE: smearing with NWChem

Hi Frank,

Try the following if you want to preserve the multiplicity with smear.

dft
=A0 mult 3
=A0 ...
=A0 ...
end
set dft:spinset t
task dft

Best regards,
-Niri

-----Original Message-----

> From: owner-nwchem-users^= emsl.pnl.gov [mailto:owner-nwchem-users^emsl.pnl.gov] On Behalf Of Van Dam, Hubertus J

Sent: Wednesday, April 06, 2011 4:08 PM
To: CCL Subscribers
Cc: nwchem-users^emsl.pnl= .gov
Subject: [NWCHEM] RE: smearing with NWChem

Hi Frank,

This is an interesting question. There are a few specific points here:
1. The energy that is associated with the smearing is normally supposed to = be negative, so the total energies with smearing should be lower than the o= nes without smearing.
2. The smearing functionality may change the spin state of your system. As = you are working on transition metal complexes I am guessing you might have = open shell systems. I can provide some special directives to control this i= f needed.
3. The code will actually print the energy that it adds on as a result of t= he smearing. Search for "eFermi=3D" in the output. (see also 4.)<= br> 4. However, if you subtract the energy from 3. you will not get the energy = you are looking for. The problem is that the DFT energy for a system with f= ractionally occupied orbitals is higher than the energy of the same system = with integer occupations. So the eFermi term that is added on corrects for = that difference and adds a bit more on top of that.
5. Concluding it seems to me that your best bet is to run all calculations = with the same smearing parameter for the final energies and compare the res= ulting energies.
I am sorry if this is not the answer you were looking for. If you want any = more specific information please feel free to contact me.

Best wishes,

=A0 =A0 =A0 =A0 Huub
________________________________________

> From: owner-chemistry+hubertus.vandam=3D=3Dpnl.gov^ccl.n= et [owner-chemistry+hubertus.vandam=3D=3Dpnl.gov^ccl= .net] On Behalf Of Xiaofeng Frank Duan duanx:_:asc.hpc.mil [owner-chemistry^ccl.net]

Sent: Wednesday, April 06, 2011 1:12 PM
To: Van Dam, Hubertus J
Subject: CCL: smearing with NWChem

Sent to CCL by: "Xiaofeng Frank Duan" [duanx^asc.hpc.mil]
Hello,

I optimized some transitional metal compounds with DFT in NWChem. For some = compounds, I had to use "smear" to get SCF converged even though = I decreased "smear" values gradually to the minimum. Since 's= mear' adds an additional energy term, the total energy is higher than t= hat of the "zero smear" for the same structure.
My question is: How to correct or scale the "smeared" total energ= y to the "zero smeared" one so that I can compare energies among = different compounds.

Thanks,
Frankhttp://www.ccl.net/c= gi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp= ://www.ccl.net/spammers.txthttp://www.ccl.net/cgi-bin/ccl/send_ccl_messageh= ttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt<= /a>>

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