[Pw_forum] About zero point energy

[Nicola Marzari]

> (5) > matdyn.x < phdos.in (Calculating phonon density of states)
> and this will produce a file called "Al.phdos" which contains the 
> phonon density of states. Now by typing:
> awk '{e=e+2*1/2}END{print e/33.357*4.1357/1000}' Al.phdos


Dear Lihui,


I would be careful in getting quantities via the integration of 
densities of states
(by the way, is it only me with this bias ?).

Every time an electronic or a phononic band goes flat you have a van
hove singularity in the density of states - to me it seems that 
integrating that
carefully requires a lot of diligence in sampling, while it would be 
straightforward
to obtain if you were doing a k-point integral.

Question for Eyvaz - does the qha code do the integrals in reciprocal
space, or via the pdos ?

nicola


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Prof Nicola Marzari   Department of Materials Science and Engineering
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