[Pw_forum] occupation
Matteo Cococcioni
matteo at umn.edu
Thu Jul 30 20:18:35 CEST 2009
the new tutorial on the calculation of U can be downloaded from this
webpage:
http://www.quantum-espresso.org/wiki/index.php/QESB09#First_week
Matteo Cococcioni wrote:
> Dear Ali,
>
> on the wiki page of quantum-espresso you should be able to find a new
> tutorial on the calculation of U. Please download it
> and run the scripts in there following the instructions.
>
>
>
> ali kazempour wrote:
>
>> Dear all
>>
>> From Linear response calculation ,I get for TiO2 bulk U=5.73, But when
>> I double the unit cell in z direction and again compute U ,I get three
>> different value for Ti atoms.(U=5.63,5.46,5.70).
>>
>>
>
> what are these three values? I assume they are what you get with
> supercells of three different sizes. is this correct? if it is the only
> strange thing is that the intermediate value is lower than the other
> two. otherwise you got pretty nice convergence of U which is what you
> want to achieve. Is there any particular reason (apart computational
> cost) why you only enlarge the cell in z direction?
>
>
>> Why these values are not same . what is the main reason? Does it in
>> numerical variation errors?
>> ANother question:
>> When we perturb D level by alpha, it give rise to change in d
>> occupancy . Is it correct that if we impose negative alpha , the
>> occupation becomes less than initial state .?
>>
>>
>
> no. positive alpha -- > decrease in total n. but you need to look at the
> right n....
>
>
>> for Ti isolated atom for apha=0.1 tr[ns(na)] after first-iteration
>> equal to the 0.002 and at the end of calculation is 2.327 while we
>> know that for Ti, tr[ns(na)] =2.000. Does it seems to be correct.?
>>
>> Number of iteration with fixed ns = 0
>> Starting ns and Hubbard U :
>> enter write_ns
>> U( 1) = 0.0000
>> alpha( 1) = 0.1000
>> atom 1 Tr[ns(na)]= 2.0000000
>> atom 1 spin 1
>> eigenvalues: 0.4000000 0.4000000 0.4000000 0.4000000 0.4000000
>> eigenvectors
>> 1 1.0000000 0.0000000 0.0000000 0.0000000 0.0000000
>> 2 0.0000000 1.0000000 0.0000000 0.0000000 0.0000000
>> 3 0.0000000 0.0000000 1.0000000 0.0000000 0.0000000
>> 4 0.0000000 0.0000000 0.0000000 1.0000000 0.0000000
>> 5 0.0000000 0.0000000 0.0000000 0.0000000 1.0000000
>> occupations
>> 0.400 0.000 0.000 0.000 0.000
>> 0.000 0.400 0.000 0.000 0.000
>> 0.000 0.000 0.400 0.000 0.000
>> 0.000 0.000 0.000 0.400 0.000
>> 0.000 0.000 0.000 0.000 0.400
>> atom 1 spin 2
>> eigenvalues: 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000
>> eigenvectors
>> 1 1.0000000 0.0000000 0.0000000 0.0000000 0.0000000
>> 2 0.0000000 1.0000000 0.0000000 0.0000000 0.0000000
>> 3 0.0000000 0.0000000 1.0000000 0.0000000 0.0000000
>> 4 0.0000000 0.0000000 0.0000000 1.0000000 0.0000000
>> 5 0.0000000 0.0000000 0.0000000 0.0000000 1.0000000
>> occupations
>> 0.000 0.000 0.000 0.000 0.000
>> 0.000 0.000 0.000 0.000 0.000
>> 0.000 0.000 0.000 0.000 0.000
>> 0.000 0.000 0.000 0.000 0.000
>> 0.000 0.000 0.000 0.000 0.000
>> nsum = 2.0000000
>> exit write_ns
>>
>>
>
> this is not the first iteration. this is what the initial guess of the
> on-site occupations the code does to start the calculation
>
>
>
>> Atomic wfc used for LDA+U Projector are NOT orthogonalized
>> Starting wfc are 9 atomic + 1 random wfc
>>
>> total cpu time spent up to now is 13.34 secs
>>
>> per-process dynamical memory: 326.3 Mb
>>
>> Self-consistent Calculation
>>
>> iteration # 1 ecut= 45.00 Ry beta=0.70
>> CG style diagonalization
>> c_bands: 3 eigenvalues not converged
>> c_bands: 2 eigenvalues not converged
>> ethr = 1.00E-12, avg # of iterations = 40.4
>> enter write_ns
>> U( 1) = 0.0000
>> alpha( 1) = 0.1000
>> atom 1 Tr[ns(na)]= 0.0021401
>> atom 1 spin 1
>> eigenvalues: 0.0000001 0.0000001 0.0000001 0.0009883 0.0009883
>> eigenvectors
>> 1 0.0000000 -0.8803392 -0.4743427 0.0000000 0.0013927
>> 2 0.0000000 -0.4743432 0.8803400 0.0000000 -0.0000040
>> 3 0.0000000 0.0012242 0.0006642 0.0000000 0.9999990
>> 4 -0.8886820 0.0000000 0.0000000 -0.4585240 0.0000000
>> 5 0.4585240 0.0000000 0.0000000 -0.8886820 0.0000000
>> occupations
>> 0.001 0.000 0.000 0.000 0.000
>> 0.000 0.000 0.000 0.000 0.000
>> 0.000 0.000 0.000 0.000 0.000
>> 0.000 0.000 0.000 0.001 0.000
>> 0.000 0.000 0.000 0.000 0.000
>>
>>
>
> this is the first iteration! the problem is, in my opinion, that you
> didn't start this calculation from wfc and potential saved from the scf
> unperturbed run, but from scratch (that's why the code has to make the
> initial guess for the n).
>
> regards,
>
> Matteo
>
>> ---------------------------------- and end of the file is
>> :
>> End of self-consistent calculation
>> enter write_ns
>> U( 1) = 0.0000
>> alpha( 1) = 0.1000
>> atom 1 Tr[ns(na)]= 2.3270531
>> atom 1 spin 1
>> eigenvalues: 0.1574294 0.1574294 0.1574294 0.9273825 0.9273825
>> eigenvectors
>> 1 0.0000000 -0.4359030 -0.7986559 0.0000000 0.4148945
>> 2 0.0000000 0.7269732 -0.0406891 0.0000000 0.6854592
>> 3 0.0000000 -0.5305643 0.6004109 0.0000000 0.5983379
>> 4 -0.9258933 0.0000000 0.0000000 -0.3777851 0.0000000
>> 5 0.3777851 0.0000000 0.0000000 -0.9258933 0.0000000
>> occupations
>> 0.927 0.000 0.000 0.000 0.000
>> 0.000 0.157 0.000 0.000 0.000
>> 0.000 0.000 0.157 0.000 0.000
>> 0.000 0.000 0.000 0.927 0.000
>> 0.000 0.000 0.000 0.000 0.157
>>
>>
>> Ali Kazempour
>> Physics department, Isfahan University of Technology
>> 84156 Isfahan, Iran. Tel-1: +98 311 391 3733
>> Fax: +98 311 391 2376 Tel-2: +98 311 391 2375
>>
>>
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>>
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>
>
>
--
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Matteo Cococcioni
Department of Chemical Engineering and Materials Science,
University of Minnesota
421 Washington Av. SE
Minneapolis, MN 55455
Tel. +1 612 624 9056 Fax +1 612 626 7246
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