[Pw_forum] Unedrstanding cohesive energy

[Mousumi Upadhyay Kahaly]

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.