[Pw_forum] binding energy of molecular oxygen

[Giuseppe Mattioli]

Only to stress the fact that you are not calculating any "free"  
energy, but only the "internal" energy, given that there is no entropy  
contribution in your calculations.
HTH
Giuseppe

Giuseppe Mattioli
ISM-CNR
Italy

Quoting Junxiang Chen <cjxxjc729 at gmail.com>:

> yes it is an isolated system
>
> this cell had been used to calculate other models kpoint has already  
> been tested to reach the convergence
>
> i just want a free energy of O2 right away so i copy the cell and  
> modify the molecule and its location directly
>
>> 在 2014年4月28日，19:34，Lorenzo Paulatto <lorenzo.paulatto at impmc.upmc.fr> 写道：
>>
>>
>>> On 04/28/2014 10:52 AM, Junxiang Chen wrote:
>>> 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
>>
>>
>> Sorry, I only just noticed the K_POINT... why are you using  
>> anything different from Gamma? This is supposed to be an isolated  
>> system, isn't it?
>>
>>
>>
>> --
>> Dr. Lorenzo Paulatto
>> IdR @ IMPMC -- CNRS & Université Paris 6
>> +33 (0)1 44 275 084 / skype: paulatz
>> http://www-int.impmc.upmc.fr/~paulatto/
>> 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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    Giuseppe Mattioli
    CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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