[Pw_forum] van der waals force

[Mehrnaz Anvari]

 Dear Paulatto
I read your discussion about , how we can sure about stability of the one 
layer material. One of your suggestion was to compare the energy of isolated 
layer with a layer in bulk, I am working on graphene and in first step I 
relaxed my system and compared the result with  graphite. the energy of 
graphite was higher than graphene. now my question is, there is van der 
waals bond in graphite and I've heard DFT calculations are  not suitable for 
this materials because of its approximation in potential .Is it correct or 
some correction is implemented in Q-E.
Also during my calculation I realized that when I increased the value of 
(celldm(3)=3-10) to attached isolated plane for graphene, there isn't any 
noticeable flactuations in total energy, but the values of subenergies such 
as hartree, ewald energy,...change extremely,I mean these terms become large 
and  I think it is not logical.What do you think?
Best Regards
Mehrnaz Anvari
Iran University Of Science & Technology 

 
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