[Pw_forum] binding energy of molecular oxygen

[Junxiang Chen]

Dear all,

 

The same problem as
http://qe-forge.org/pipermail/pw_forum/2009-November/089525.html , the
binding energy of detached O2 is 6.57eV, which is far from experiment value
( 5.12eV ), or 5.7eV in this page.

 

 

Input file ( O2 ):

 

&SYSTEM

                       ibrav = 12,

                   celldm(1) = 16.0348541363689,

                   celldm(2) = 1.52752767,

                   celldm(3) = 2.665651575,

                   celldm(4) = -0.3273333438252,

                         nat = 2,

                        ntyp = 1,

                     ecutwfc = 45,

                     ecutrho = 400,

                 occupations = 'smearing' ,

                     degauss = 0.01,

                    smearing = 'methfessel-paxton' ,

                       nspin = 2,

   starting_magnetization(1) = 1,

/

&ELECTRONS

            electron_maxstep = 200,

                    conv_thr = 1.D-6,

                 mixing_beta = 0.4,

                 mixing_mode = 'local-TF' ,

/

&IONS

                ion_dynamics = 'bfgs' ,

/

ATOMIC_SPECIES

   O     15.9994      O.pbe-rrkjus.UPF

ATOMIC_POSITIONS crystal

O        0.217969593   0.389882242   0.401960243

O        0.217971037   0.389881524   0.456565745

K_POINTS automatic

  5 5 2   0 0 0

 

 

The binding energy is calculated by BE=EO2-2*EO* and BE=6.57eV 

 

 

 

Could anyone tells me what's wrong? 

 

 

-------------------------------------------------------

Junxiang Chen 

Ph.D. candidate

Department of chemistry and molecular

Wuhan University 

Wuhan, China

Email: cjxxjc729 at gmail.com <mailto:cjxxjc729 at gmail.com> 

 

 

-------------------------------------------------------

Junxiang Chen 

Ph.D. candidate

Department of chemistry and molecular

Wuhan University 

Wuhan, China

Email: cjxxjc729 at gmail.com

QQ: 95508097

 

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