[Wien] New exchange-correlation potential

[yhzhao]

Hello all,

It looks like the error is due to the mkl. When I change the math lib to 
that given by wien, it give a band gap of about 1.6 eV.
It is curious.

yonghong

On 2010年06月10日 10:11, F. Tran wrote:
> You are using -p to do a parallel calculation and another user has just
> reported a bug for parallel calculations with MBJ (see the previous
> email of P. Blaha in the WIEN2k mailing list). Try also without -p.
>
>
> On Thu, 10 Jun 2010, yhzhao wrote:
>
>    
>> Hello,
>>
>> I have got a band gap of 0.8 eV, with lattice constant 5.6533 Angstrom and the
>> space group No. is 216, with two atoms in (0.0 0.0 0.0) and (0.25 0.25 0.25).
>>
>> I have checked that:
>>
>> 1. In GaAs.inm_vresp, YES has been replaced by NO;
>> 2. I have done the calculation as following steps:
>>      For the first scf run, I have set NR2V and indxc=5 in GaAs.in0;
>>      Change NR2V to R2V and run one more scf cycle;
>>      save lda;
>>      Set indxc=28 in GaAs.in0;
>>      cp GaAs.in0 GaAs.in0_grr and set index=50 in GaAs.in0_grr
>>      run_lapw -p -cc 0.00001
>>      plot bandstructure
>>
>> Anything wrong with my procedure?
>>
>> yonghong
>> On 2010年06月10日 05:06, F. Tran wrote:
>>      
>>> Which value do you obtain? Did you use the correct structure?
>>> In Table 1 of the following paper:
>>> Tran et al., J. Phys.: Condens. Matter 19, 196208 (2007)
>>> it is indicated which structure and lattice constant were used.
>>>
>>> In case.inm_vresp, you have to replace YES by NO for the normalization.
>>>
>>>
>>> On Wed, 9 Jun 2010, yhzhao wrote:
>>>
>>>
>>>        
>>>> Hi,
>>>> I have do all your suggested things, which given in the usersguide.
>>>> However I
>>>> cannot get the band gap, that is 1.64 eV for GaAs, as suggested by PRL
>>>> 102,
>>>> 226401 (2009).
>>>>
>>>>
>>>> yonghong
>>>> On 2010年06月09日 17:54, F. Tran wrote:
>>>>
>>>>          
>>>>> Hello,
>>>>>
>>>>> In order to use the modified Becke-Johnson exchange potential
>>>>> you have to choose indxc=28 in case.in0 and indxc=50 in case.in0_grr.
>>>>>
>>>>> A few more things:
>>>>>
>>>>> In case.in0 you also need to replace NR2V by R2V such that the
>>>>> exchange-correlation potential is written in case.r2v, which will
>>>>> be used in the next iteration.
>>>>>
>>>>> You need case.inm_vresp such that case.vrespsum (which contains a
>>>>> part of the kinetic-energy density) is created.
>>>>>
>>>>> There is no adjustable parameters.
>>>>>
>>>>> The LDA correlation potential is added to the MBJ exchange potential.
>>>>>
>>>>> The LDA exchange-correlation functional is used for the energy.
>>>>>
>>>>> The MBJ exchange potential is not the derivative of an energy
>>>>> functional,
>>>>> which means that the method is not variational (i.e., the orbitals are
>>>>> not the ones which minimize the total energy, which is LDA).
>>>>> In particular, it means that you can not use forces to optimize internal
>>>>> parameters.
>>>>>
>>>>>
>>>>> On Wed, 9 Jun 2010, yhzhao wrote:
>>>>>
>>>>>
>>>>>
>>>>>            
>>>>>> Dear Prof. Pblaha,
>>>>>>
>>>>>> I have tried to calculate something using the new exchange potential
>>>>>> with indxc=50 as suggested by the usersguide. At first I want to
>>>>>> repeat
>>>>>> some data given by PRL 102, 226401 (2009), for example, the band gap
>>>>>> of
>>>>>> GaAs. I can get a band gap of 0.7 eV for GaAs, which is much better
>>>>>> than
>>>>>> 0.3 eV of lda, but not much better than the value given by you in PRL
>>>>>> 102, 226401 (2009). In the calculation, I use the experimental lattice
>>>>>> constant. The k-grid have been increased as dense as 20x20x20 and
>>>>>> RKmax
>>>>>> as large as 9.0.
>>>>>>
>>>>>> Is there any adjustable parameter for the MBJ calculation? Thanks.
>>>>>>
>>>>>> Regards,
>>>>>>
>>>>>> yonghong
>>>>>>
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>>>>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>>>>>
>>>>>>
>>>>>>
>>>>>>              
>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>>            
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>>>>
>>>>
>>>>
>>>>
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>>>>          
>>      
>>
>>
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