[CPMD-list] How to compare calculated result with reference data?

[Axel Kohlmeyer]

On Fri, 2 Feb 2007, Tengfei Luo wrote:

TL> oh, I see now! Thank you for your help. So, I should check the lattice 
TL> constant and the bulk modulus to see if my calculation is correct? Am I 
TL> right?

yes. that would be one way.

please note that there are a number of factors that affect
accuracy, e.g. pseudopotential, cutoff, k-point sampling
and so on.

axel. 

TL> 
TL> 
TL> ----- Original Message ----- 
TL> From: "Axel Kohlmeyer" <akohlmey at cmm.chem.upenn.edu>
TL> To: "Tengfei Luo" <luotengf at msu.edu>
TL> Cc: "Cpmd-List (E-mail)" <cpmd-list at cpmd.org>
TL> Sent: Friday, February 02, 2007 3:59 PM
TL> Subject: Re: [CPMD-list] How to compare calculated result with reference 
TL> data?
TL> 
TL> 
TL> > On Fri, 2 Feb 2007, Tengfei Luo wrote:
TL> >
TL> > TL> Dear all:
TL> > TL> I'm learnning how to use CPMD. I did some wavefunction optimization of 
TL> > bulk
TL> > TL> Si and wanted to check if the calculation was correct. So, I get the
TL> > TL> Etot/atom from my calculation (-107.56eV) and compared to a reference 
TL> > I
TL> > TL> found online with a value of -107.90eV using LDA. The result seem to 
TL> > be OK.
TL> >
TL> > please note that with CPMD you are using pseudopotentials and the total
TL> > energy depends on the construction of the pseudopotenial.
TL> >
TL> > TL> However, I found somewhere else has a value of Etot of -288.198397 
TL> > hatree
TL> > TL> (http://physics.nist.gov/PhysRefData/DFTdata/Tables/14Si.html). I'm 
TL> > now
TL> > TL> confused. How should I check my calculation? I did searched the 
TL> > archive but
TL> >
TL> > furthermore, the part that is 'integrated out' during the
TL> > pseudopotential generation is missing in the total energy that
TL> > you see, so you cannot compare it to all electron data.
TL> >
TL> >
TL> > cheers,
TL> >    axel.
TL> >
TL> > TL> didn't found anything. I hope someone can help me. Thank you in 
TL> > advance.
TL> > TL>
TL> > TL> Regards,
TL> > TL>
TL> > TL> T.Luo
TL> > TL>
TL> > TL> _______________________________________________
TL> > TL> CPMD-list mailing list
TL> > TL> CPMD-list at cpmd.org
TL> > TL> http://cpmd.org/mailman/listinfo/cpmd-list
TL> > TL>
TL> >
TL> > -- 
TL> > =======================================================================
TL> > Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
TL> >   Center for Molecular Modeling   --   University of Pennsylvania
TL> > Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
TL> > tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
TL> > =======================================================================
TL> > If you make something idiot-proof, the universe creates a better idiot.
TL> >
TL> > 
TL> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.