[Pw_forum] A little question about total energy

NoahPark baknoo at tokyo.rist.or.jp
Mon May 26 13:43:07 CEST 2003

Dear Users;
If USPP and NCPP are simultaneously used in the description of a certain
heterogeneous structure(with the same exchange-correlation functional),
is there any problem to figure out the total energy and binding energy ?

Best regards,

Noah

----- Original Message -----
From: "Paolo Giannozzi" <giannozz at nest.sns.it>
To: <pw_forum at pwscf.org>
Sent: Friday, May 16, 2003 10:28 PM
Subject: Re: [Pw_forum] A little question about total energy

> Hi
>
> >    In the output of PWSCF, the energy partitions are list
> > following the total energy as I pasted below. I found
> > that the total energy is not equal to the sum of those listed
> > partitions.
>
> Total Energy = sum of terms marked with "+" below =
>     one-electron + hartree + xc + ewald + correction for metals
>
> !    total energy              =   -62.07569469 ryd
>      estimated scf accuracy    <     0.00000799 ryd
>
>      band energy sum           =   -14.82580512 ryd
> +    one-electron contribution =   -98.79712762 ryd
> +    hartree contribution      =    51.10053218 ryd
> +    xc contribution           =   -14.02297161 ryd
> +    ewald contribution        =    -0.34484385 ryd
>       scf in/out correction     =     0.02901784 ryd
> +    correction for metals     =    -0.01128379 ryd
>
> The "one-electron contribution" is the kinetic + ionic term:
>   \sum <psi| T + V_ion | psi>
> The "band energy sum" is exactly what it claims to be:
>   \sum epsilon = \sum <psi| T + V_ion + V_scf | psi>
> The "correction for metals" makes forces and energies
> consistent if a broadening scheme is used.
> The "scf in/out correction" is no longer used
> (and no longer useful)
> The "estimated scf accuracy" gives an estimate of the
> error on the energy due to imperfect self-consistency.
>
> Admittedly, it is slightly confusing.
>
> Paolo
>
> --
> Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
> Scuola Normale Superiore    Phone:   +39/050509412
> Piazza dei Cavalieri 7      Fax:     +39/050509417, 050563513
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>
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