[Wien] A basic question about GGA+U approach

2012-06-26 Thread shamik chakrabarti 
Dear wien2k users,

   We generally choose the value of U by fitting it with experimental
band gap or by calculating it through linear response method. Now my
question is that whether U is element specific or depends on the composite
in which the element reside? (*if I consider same magnetic configuration
for all the composites I am referring here...as antiferromagntism do
produce a band gap even without applying any U*)

To make it more clear, say for Fe d, I have seen in literature, people have
used U=4.5 to 5 eV..in some of our calculation we have even used U=6 eV
for Fe d to obtain better electronic structure having closer match with
experimental observation. Hence it looks that U for Fe d orbital can have
value ranging from 4.5-6 eV...& that mean U is not element specific rather
it depends on the composite in which the element exist (I again want to
insist that if I consider same magnetic configuration for all the
composites). Am I right?

with regards,

-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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[Wien] A basic question about GGA+U approach

2012-06-26 Thread Peter Blaha 
Yes, U depends on the type of atom, but of course also on the specific 
compound.
For metallic Fe the U should be in the range of 0-2 eV at most, for some 
insulating compound with very localized states, it may go up to even 4-6 
(maybe even 8) eV.

Am 26.06.2012 06:42, schrieb shamik chakrabarti:
> Dear wien2k users,
>
> We generally choose the value of U by fitting it with
> experimental band gap or by calculating it through linear response
> method. Now my question is that whether U is element specific or depends
> on the composite in which the element reside? (*if I consider same
> magnetic configuration for all the composites I am referring here...as
> antiferromagntism do produce a band gap even without applying any U*)
>
> To make it more clear, say for Fe d, I have seen in literature, people
> have used U=4.5 to 5 eV..in some of our calculation we have even
> used U=6 eV for Fe d to obtain better electronic structure having closer
> match with experimental observation. Hence it looks that U for Fe d
> orbital can have value ranging from 4.5-6 eV...& that mean U is not
> element specific rather it depends on the composite in which the element
> exist (I again want to insist that if I consider same magnetic
> configuration for all the composites). Am I right?
>
> with regards,
>
> --
> Shamik Chakrabarti
> Senior Research Fellow
> Dept. of Physics & Meteorology
> Material Processing & Solid State Ionics Lab
> IIT Kharagpur
> Kharagpur 721302
> INDIA
>
>
> ___
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>

-- 
Peter Blaha
Inst.Materials Chemistry
TU Vienna
Getreidemarkt 9
A-1060 Vienna
Austria
+43-1-5880115671

[Wien] A basic question about GGA+U approach

2012-06-26 Thread shamik chakrabarti 
Dear Prof. Peter Blaha,

Thank you very much for your reply. I got my answer.

with best regards,

On Tue, Jun 26, 2012 at 11:19 AM, Peter Blaha
wrote:

> Yes, U depends on the type of atom, but of course also on the specific
> compound.
> For metallic Fe the U should be in the range of 0-2 eV at most, for some
> insulating compound with very localized states, it may go up to even 4-6
> (maybe even 8) eV.
>
> Am 26.06.2012 06:42, schrieb shamik chakrabarti:
>
>> Dear wien2k users,
>>
>>We generally choose the value of U by fitting it with
>> experimental band gap or by calculating it through linear response
>> method. Now my question is that whether U is element specific or depends
>> on the composite in which the element reside? (*if I consider same
>>
>> magnetic configuration for all the composites I am referring here...as
>> antiferromagntism do produce a band gap even without applying any U*)
>>
>>
>> To make it more clear, say for Fe d, I have seen in literature, people
>> have used U=4.5 to 5 eV..in some of our calculation we have even
>> used U=6 eV for Fe d to obtain better electronic structure having closer
>> match with experimental observation. Hence it looks that U for Fe d
>> orbital can have value ranging from 4.5-6 eV...& that mean U is not
>> element specific rather it depends on the composite in which the element
>> exist (I again want to insist that if I consider same magnetic
>> configuration for all the composites). Am I right?
>>
>> with regards,
>>
>> --
>> Shamik Chakrabarti
>> Senior Research Fellow
>> Dept. of Physics & Meteorology
>> Material Processing & Solid State Ionics Lab
>> IIT Kharagpur
>> Kharagpur 721302
>> INDIA
>>
>>
>> __**_
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.**at 
>> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien
>>
>>
> --
> Peter Blaha
> Inst.Materials Chemistry
> TU Vienna
> Getreidemarkt 9
> A-1060 Vienna
> Austria
> +43-1-5880115671
>
>
> __**_
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.**at 
> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien
>



-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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[Wien] A basic question about GGA+U approach

2012-06-26 Thread Haranath Ghosh 
Dear experienced Users and developer Wien2k,
?
?Is it possible to use U value for Oxygens with l=1 orbitals. I always get 
error. Thanks for your response.
?
with best regards, Haranath Ghosh

--- On Tue, 6/26/12, shamik chakrabarti  wrote:


From: shamik chakrabarti 
Subject: Re: [Wien] A basic question about GGA+U approach
To: "A Mailing list for WIEN2k users" 
List-Post: wien@zeus.theochem.tuwien.ac.at
Date: Tuesday, June 26, 2012, 6:37 PM


Dear Prof. Peter Blaha,


? ? ? ? ? ? Thank you very much for your reply. I got my answer.


with best regards,


On Tue, Jun 26, 2012 at 11:19 AM, Peter Blaha  
wrote:

Yes, U depends on the type of atom, but of course also on the specific compound.
For metallic Fe the U should be in the range of 0-2 eV at most, for some 
insulating compound with very localized states, it may go up to even 4-6 (maybe 
even 8) eV.

Am 26.06.2012 06:42, schrieb shamik chakrabarti:


Dear wien2k users,

? ? ? ?We generally choose the value of U by fitting it with
experimental band gap or by calculating it through linear response
method. Now my question is that whether U is element specific or depends
on the composite in which the element reside? (*if I consider same

magnetic configuration for all the composites I am referring here...as
antiferromagntism do produce a band gap even without applying any U*)


To make it more clear, say for Fe d, I have seen in literature, people
have used U=4.5 to 5 eV..in some of our calculation we have even
used U=6 eV for Fe d to obtain better electronic structure having closer
match with experimental observation. Hence it looks that U for Fe d
orbital can have value ranging from 4.5-6 eV...& that mean U is not
element specific rather it depends on the composite in which the element
exist (I again want to insist that if I consider same magnetic
configuration for all the composites). Am I right?

with regards,

--
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA


___
Wien mailing list
Wien at zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien


-- 
Peter Blaha
Inst.Materials Chemistry
TU Vienna
Getreidemarkt 9
A-1060 Vienna
Austria
+43-1-5880115671


___
Wien mailing list
Wien at zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien




-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA

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[Wien] A basic question about GGA+U approach

2012-06-26 Thread Shamik Chakrabarti 
Dear Haranath Ghosh,

 Yes U can be used for p orbital of oxygen...but what value of U
you are going to use that depends on the system and the problem you are
studied.& also what error you are getting??...that is not clear from
your mail

with regards,

On Tue, Jun 26, 2012 at 6:48 PM, Haranath Ghosh wrote:

> Dear experienced Users and developer Wien2k,
>
>  Is it possible to use U value for Oxygens with l=1 orbitals. I always get
> error. Thanks for your response.
>
> with best regards, Haranath Ghosh
>
> --- On *Tue, 6/26/12, shamik chakrabarti * wrote:
>
>
> From: shamik chakrabarti 
> Subject: Re: [Wien] A basic question about GGA+U approach
> To: "A Mailing list for WIEN2k users" 
> Date: Tuesday, June 26, 2012, 6:37 PM
>
>
> Dear Prof. Peter Blaha,
>
> Thank you very much for your reply. I got my answer.
>
> with best regards,
>
> On Tue, Jun 26, 2012 at 11:19 AM, Peter Blaha <
> pblaha at 
> theochem.tuwien.ac.at<http://us.mc1606.mail.yahoo.com/mc/compose?to=pblaha at 
> theochem.tuwien.ac.at>
> > wrote:
>
> Yes, U depends on the type of atom, but of course also on the specific
> compound.
> For metallic Fe the U should be in the range of 0-2 eV at most, for some
> insulating compound with very localized states, it may go up to even 4-6
> (maybe even 8) eV.
>
> Am 26.06.2012 06:42, schrieb shamik chakrabarti:
>
> Dear wien2k users,
>
>We generally choose the value of U by fitting it with
> experimental band gap or by calculating it through linear response
> method. Now my question is that whether U is element specific or depends
> on the composite in which the element reside? (*if I consider same
>
> magnetic configuration for all the composites I am referring here...as
> antiferromagntism do produce a band gap even without applying any U*)
>
>
> To make it more clear, say for Fe d, I have seen in literature, people
> have used U=4.5 to 5 eV..in some of our calculation we have even
> used U=6 eV for Fe d to obtain better electronic structure having closer
> match with experimental observation. Hence it looks that U for Fe d
> orbital can have value ranging from 4.5-6 eV...& that mean U is not
> element specific rather it depends on the composite in which the element
> exist (I again want to insist that if I consider same magnetic
> configuration for all the composites). Am I right?
>
> with regards,
>
> --
> Shamik Chakrabarti
> Senior Research Fellow
> Dept. of Physics & Meteorology
> Material Processing & Solid State Ionics Lab
> IIT Kharagpur
> Kharagpur 721302
> INDIA
>
>
> __**_
> Wien mailing list
> Wien at 
> zeus.theochem.tuwien.ac.**at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien
>  at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
>
>
> --
> Peter Blaha
> Inst.Materials Chemistry
> TU Vienna
> Getreidemarkt 9
> A-1060 Vienna
> Austria
> +43-1-5880115671
>
>
> __**_
> Wien mailing list
> Wien at 
> zeus.theochem.tuwien.ac.**at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien
>  at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
>
>
>
>
> --
> Shamik Chakrabarti
> Senior Research Fellow
> Dept. of Physics & Meteorology
> Material Processing & Solid State Ionics Lab
> IIT Kharagpur
> Kharagpur 721302
> INDIA
>
> -Inline Attachment Follows-
>
>
> ___
> Wien mailing list
> Wien at 
> zeus.theochem.tuwien.ac.at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien 
> at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
>
> ___
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
>


-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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[Wien] A basic question about GGA+U approach

2012-06-26 Thread Laurence Marks 
A general comment: you may want to use the onsite exact-exchange instead of
LDA/GGA+U. It is less sensitive to the precise environment. However, in my
experience this (and LDA/GGA+U) is better just of d-orbitals, and less
effective for O p levels.

On Tue, Jun 26, 2012 at 10:47 AM, Shamik Chakrabarti  wrote:

>  Dear Haranath Ghosh,
>
>   Yes U can be used for p orbital of oxygen...but what value of U
> you are going to use that depends on the system and the problem you are
> studied.& also what error you are getting??...that is not clear from
> your mail
>
>  with regards,
>
> On Tue, Jun 26, 2012 at 6:48 PM, Haranath Ghosh  yahoo.com>wrote:
>
>>   Dear experienced Users and developer Wien2k,
>>
>>  Is it possible to use U value for Oxygens with l=1 orbitals. I always
>> get error. Thanks for your response.
>>
>> with best regards, Haranath Ghosh
>>
>> --- On *Tue, 6/26/12, shamik chakrabarti * wrote:
>>
>>
>> From: shamik chakrabarti 
>> Subject: Re: [Wien] A basic question about GGA+U approach
>> To: "A Mailing list for WIEN2k users" 
>> Date: Tuesday, June 26, 2012, 6:37 PM
>>
>>
>> Dear Prof. Peter Blaha,
>>
>>  Thank you very much for your reply. I got my answer.
>>
>>  with best regards,
>>
>> On Tue, Jun 26, 2012 at 11:19 AM, Peter Blaha <
>> pblaha at 
>> theochem.tuwien.ac.at<http://us.mc1606.mail.yahoo.com/mc/compose?to=pblaha 
>> at theochem.tuwien.ac.at>
>> > wrote:
>>
>> Yes, U depends on the type of atom, but of course also on the specific
>> compound.
>> For metallic Fe the U should be in the range of 0-2 eV at most, for some
>> insulating compound with very localized states, it may go up to even 4-6
>> (maybe even 8) eV.
>>
>> Am 26.06.2012 06:42, schrieb shamik chakrabarti:
>>
>> Dear wien2k users,
>>
>>We generally choose the value of U by fitting it with
>> experimental band gap or by calculating it through linear response
>> method. Now my question is that whether U is element specific or depends
>>  on the composite in which the element reside? (*if I consider same
>>
>> magnetic configuration for all the composites I am referring here...as
>>  antiferromagntism do produce a band gap even without applying any U*)
>>
>>
>> To make it more clear, say for Fe d, I have seen in literature, people
>> have used U=4.5 to 5 eV..in some of our calculation we have even
>> used U=6 eV for Fe d to obtain better electronic structure having closer
>> match with experimental observation. Hence it looks that U for Fe d
>> orbital can have value ranging from 4.5-6 eV...& that mean U is not
>> element specific rather it depends on the composite in which the element
>> exist (I again want to insist that if I consider same magnetic
>> configuration for all the composites). Am I right?
>>
>> with regards,
>>
>> --
>> Shamik Chakrabarti
>> Senior Research Fellow
>> Dept. of Physics & Meteorology
>> Material Processing & Solid State Ionics Lab
>> IIT Kharagpur
>> Kharagpur 721302
>> INDIA
>>
>>
>>  __**_
>> Wien mailing list
>> Wien at 
>> zeus.theochem.tuwien.ac.**at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien
>>  at zeus.theochem.tuwien.ac.at>
>> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
>>
>>
>> --
>> Peter Blaha
>> Inst.Materials Chemistry
>> TU Vienna
>> Getreidemarkt 9
>> A-1060 Vienna
>> Austria
>> +43-1-5880115671
>>
>>
>> __**_
>> Wien mailing list
>> Wien at 
>> zeus.theochem.tuwien.ac.**at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien
>>  at zeus.theochem.tuwien.ac.at>
>> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
>>
>>
>>
>>
>>  --
>> Shamik Chakrabarti
>> Senior Research Fellow
>> Dept. of Physics & Meteorology
>> Material Processing & Solid State Ionics Lab
>> IIT Kharagpur
>> Kharagpur 721302
>> INDIA
>>
>>  -Inline Attachment Follows-
>>
>>
>> ___
>> Wien mailing list
>> Wien at 
>> zeus.theochem.tuwien.ac.at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien
>>  at zeus.th