[Pw_forum] Rydberg to KJ/mole - polymorphs

[Guntram Schmidt]

Thanks for the fast reply!

This leaves me to the problem of the interpretation of the results.

Has anyone experience with the calculation of polymorphic molecular 
crystals?

My energy differences of 120 and 240 kJ/mole are far too high for 
polymorphs (see ref [1]).
Am I mistaken to equalize the "total energy" of pwscf-output with the 
"lattice energy" (former "structure energy")?
I'm aware of the missing Entropy - but it is told to be negligible small...

I do use nc pseudopotentials and my system is composed of 
triphenylphosphine moities with aminobenzoic acids connected.
I'll attach the input lines [2].

Thanks a lot for further assistance,
Guntram


[1] Gavezzotti, A., & Filippini, G. (1995). Polymorphic Forms of Organic 
Crystals at Room Conditions: Thermodynamic and Structural Implications. 
Journal of the American Chemical Society, 117(49), 12299-12305. 
doi:10.1021/ja00154a032

[2]
&control
    calculation = 'scf',
    restart_mode='from_scratch',
    prefix='i2t0491.xyz.50.200',
    tstress = .true.,
    tprnfor = .true.,
    pseudo_dir = '/pseudo/',
    outdir='/tmp/i2t0491.xyz.50.200/',
    verbosity = 'high',
/
&system
  ibrav = 14,
  A = 14.8387,
  B = 14.8390,
  C = 18.0441,
  cosAB = 0,
  cosAC = 0,
  cosBC = 0,
  nat = 392,
  ntyp = 5,
  occupations = 'fixed',
  ecutwfc = 50,
  ecutrho = 200,
  input_dft = 'vdW-DF',
/
&electrons
     conv_thr        = 1.0d-8,
     electron_maxstep= 1000,
/


ATOMIC_SPECIES
  P 1.0 P.rpb-nc.UPF
  O 1.0 O.rpb-nc.UPF
  N 1.0 N.rpb-nc.UPF
  H 1.0 H.rpb-nc.UPF
  C 1.0 C.rpb-nc.UPF


ATOMIC_POSITIONS angstrom
  C       2.883901    5.973588   10.295242
.
.
.
K_POINTS automatic
1 1 1 0 0 0




Am 21.03.2012 14:29, schrieb Tone Kokalj:
> On Wed, 2012-03-21 at 14:21 +0100, Guntram Schmidt wrote:
>> Hello together,
>>
>> I'm sure, this question has been already asked - but lacking a search
>> function for the pw_forum and not having found something using google,
>> I'm urged to ask this question to the list:
>>
>> How do I convert the output of pwscf (which is in Ry) to kJ per mole?
>
> ?
> --
>
> 1.0 ry =
>      = 0.5 hartree
>      = 1.0 ry
>      = 13.605691930242388 eV
>      = 1312.7496997450642 kJ/mol
>      = 313.75470835207074 kcal/mol
>      = 2.17987197e-21 kJ
>      = 5.21001904875717e-22 kcal
>      = 2.1798719700000002e-11 erg
>
> As a convenience you may use the "unitconv" utility of xcrysden
> (attached).
>
> Regards, Tone
>
>
>
>
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