Dear Matteo
I follow? your link and is useful for me, but when I want to study a? 
nonmagnetic material like Tio2 ,how do I change the format of pos_file.? for 
NiO it is in tutorial ,but NiO is antiferromagnetic and in pos_nio.r16 you add 
a switch 1,-1 and 0 in front of atomic type. but for TiO2, it is nonmagnetic. 
How can I define the differnet type?
thanks a lot

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

--- On Thu, 7/30/09, Matteo Cococcioni <matteo at umn.edu> wrote:

From: Matteo Cococcioni <[email protected]>
Subject: Re: [Pw_forum] occupation
To: "PWSCF Forum" <pw_forum at pwscf.org>
Date: Thursday, July 30, 2009, 11:18 AM


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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>>???
>>? ???
>
>
>???


-- 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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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