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["zzzhong" <zzzhong@red.semi.ac.cn>]

Dear abinit user,hello!
     About the effective mass, I have some questions. Because the LDA 
underestimate the energy gap(Eg). the couple between the conduction band and 
the valence band  is modified. I am afraid that the effective mass of the 
electron in the Gamma point is underestimate. Maybe the GW caculation can 
resolve this problem. But for the big supercell, the GW calculation is a big 
problem. Do we have another method to resolve this problem.  
        

======= 2006-11-21 20:07:51 您在来信中写道：=======

>
>On 21 Nov 2006, at 12:27, Geoffrey Stenuit wrote:
>
>> Xiao Deng wrote:
>>
>>> Dear abinit user,
>>>        I want to get the effective mass of the electrons and  
>>> holes. Can anybody give me some advice? Thanks!
>>>  Xiao Deng
>>
>> Dear Xiao Deng,
>>
>> An easy way to get the effective mass is simply to compute the  
>> energy dispersion in the vicinity of the k-point where you would  
>> like to calculate the mass (See the abinit tutorial, lesson 3 for  
>> more details about the computation of the band structure). Using  
>> the relation,
>> $E(k)=\frac{\hbar^2k^2}{2m^*}$,
>> you then need to fit the energy dispersion with a quadratic law $E 
>> (k)=Ck^2$, the quadratic coefficient C being inversely proportional  
>> to the effective mass.
>>
>> Good luck,
>>
>> Joe
>
>RIght. Note however the following subtlety : the number of planewaves  
>may vary
>with the k point, causing some numerical noise. To avoid this noise  
>in the eigenenergy curves, simply
>use a non-zero ecutsm (the recommended value of 0.5 Ha should be OK).
>
>Xavier

= = = = = = = = = = = = = = = = = = = =
   Best regards
                                 
　 zzzhong
   State Key Laboratory for Superlattices and Microstructures
　 Institute of Semiconductors
   Chinese Academy of Sciences
   P. O. Box 912, Beijing 100083
　 Eamil: zzzhong@red.semi.ac.cn
　 2006-11-22