[Pw_forum] Band Gap Significance

[Paolo Giannozzi]

On Friday 16 June 2006 17:59, Luke Thulin wrote:

> As I understand it, DFT has a known inability to predict the band 
> gap properly compared to measured values. [....] would relative
> values be valid, if for example, I wanted to calculate the percent
> change in band gap due to stress? 

the conventional wisdom is that changes in the band gaps are 
better reproduced by DFT than band gaps themselves. It is
debatable whether the conventional wisdom is based on the 
comparison of actual calculations with experiments, or on clear 
theoretical arguments,  or on the lack of better approximations 
for realistic materials! 

Paolo
-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
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