Clarification of the Total Energy Components in the OUTCAR

[Modey3]

Hello,

For bulk Fe the breakdown of the Total Energy components after self consistency has been reached is:

alpha Z PSCENC = 72.38939815
Ewald energy TEWEN = -587.98526919
-1/2 Hartree DENC = -67.89875186
-V(xc)+E(xc) XCENC = -249.94822743
PAW double counting = 0.00000000
entropy T*S EENTRO = 0.00000000
eigenvalues EBANDS = 21.17739166
atomic energy EATOM = 803.96357036

The sum of these components is the total energy. What exactly is the alpha Z and eigenvalues energy components? More importantly, why does the Hartree Energy component reduce the Total Energy? Shouldn't the Hartree component raise the Total Energy of the system? Any info would be appreciated. Thanks.

Best Regards

modey3

[forsdan]

For the short answer, please have a look a this previous thread:
http://cms.mpi.univie.ac.at/vasp-forum/ ... .php?4.273

and also look at the total energy expression at page 14 in
http://cms.mpi.univie.ac.at/vasp-worksh ... introd.pdf

Please notice that the Hartree energy itself is positive. However, you'll have a "-1/2 Hartree" contribution to the total energy as a double counting correction.

For a more in depth understanding of the different terms and their implementation I recommend you to read a DFT textbook, e.g.

Jorge Kohanoff, Electronic structure calculations for solids and molecules
or/and
Richard M. Martin, Electronic Structure: Basic Theory and Practical Methods

which cover these topics very well.


Cheers,
/Dan



<span class='smallblacktext'>[ Edited Thu Jul 16 2009, 10:08AM ]</span>

[Modey3]

forsdan,

Thanks for the response.

http://cms.mpi.univie.ac.at/vasp-worksh ... introd.pdf

Helped.


Best Regards

modey3