[Pw_forum] [Fwd: Unedrstanding cohesive energy]

[Mousumi Upadhyay Kahaly]

Dear All,

In addition to the last mail, I should have mentioned that-
      total energy is being obtained if we add other terms except "band
energy sum" i.e. total energy = "one-electron contribution" +
"hartree contribution" + "xc contribution" + "ewald contribution" +
"correction for metals ".
       Any help to understand this is appreciated.  regards. mousumi.
---------------------------- Original Message ----------------------------
Subject: Unedrstanding cohesive energy
From:    mousumi at jncasr.ac.in
Date:    Tue, June 28, 2005 1:38 pm
To:      pw_forum at pwscf.org
--------------------------------------------------------------------------

Dear All,


       While running pw.x for relaxation, I find that At the end of the
output file, "total energy" is printed along with "band energy
sum", "one-electron contribution", "hartree contribution", "xc
contribution", "ewald contribution", "  correction for metals ".

       But 2 times band energy(due to presence of 2 e per band) plus the
other terms does not give exactly the total energy value. Why is
so?
For example, for a single C atoms in a big box, as the output file shows-
================================================================
!    total energy              =   -10.71816942 ryd
     estimated scf accuracy    <     0.00000000 ryd

     band energy sum           =    -2.76868763 ryd
     one-electron contribution =   -12.12935309 ryd
     hartree contribution      =     6.49924911 ryd
     xc contribution           =    -2.81598725 ryd
     ewald contribution        =    -2.26983804 ryd
     correction for metals     =    -0.00224015 ryd
================================================================

       I actually want to understand the contribution of these terms to
the cohesive energy of the system. Can you please help me in this
regard?

        Thanks and regards,   mousumi.