[Pw_forum] binding energy of molecular oxygen

[Junxiang Chen]

Input file (O) almost the same as O2

 

/

&SYSTEM

                       ibrav = 12,

                   celldm(1) = 16.0348541363689,

                   celldm(2) = 1.52752767,

                   celldm(3) = 2.665651575,

                   celldm(4) = -0.3273333438252,

                         nat = 1,

                        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

K_POINTS automatic

  5 5 2   0 0 0

 

nspin and  starting_magnetization(1)  have been set

 

 

thank you for your reply!

Best wishes

 

From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
Behalf Of Lorenzo Paulatto
Sent: Monday, April 28, 2014 4:24 PM
To: PWSCF Forum
Subject: Re: [Pw_forum] binding energy of molecular oxygen

 

How did you compute EO? You need to use spin polarization and to break
symmetry in order to get the lowest possible energy (i.e. Hund's rule).

kind regards

On 04/28/2014 10:06 AM, Junxiang Chen wrote:

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 <mailto:cjxxjc729 at gmail.com> 

QQ: 95508097

 






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-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
+33 (0)1 44 275 084 / skype: paulatz
http://www-int.impmc.upmc.fr/~paulatto/
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