[Wien] How to fit birch Murnaghan EOS for the orthorhombic case

Fecher, Gerhard fecher at uni-mainz.de
Mon May 29 14:49:02 CEST 2017 

Just to mention:
this (the 2nd order equation to fit the lattice parameters) is not the Birch-Murnaghan equation of state that describes the dependence of the volume on the applied pressure (for very high pressure)
and that is usually used to find the energy-Volume relation under hydrostatic pressure.




Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von delamora [delamora at unam.mx]
Gesendet: Sonntag, 28. Mai 2017 17:26
An: wien at zeus.theochem.tuwien.ac.at
Betreff: Re: [Wien] How to fit birch Murnaghan EOS for the orthorhombic case

The equation you should fit is

F(x,y,z)=a+bx+cy+dz+exy+fxz+gyz+hx^2+iy^2+jz^2

where x,y,z correspond to the lattice parameters A,B,C

This is "parabolic" in the 3 dimensions, you have 10 parameters to fit (a,b,c...) and 10 data points


________________________________
De: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> en nombre de BUSHRA SABIR <b_sabir437 at yahoo.com>
Enviado: sábado, 27 de mayo de 2017 02:32 p. m.
Para: wien at zeus.theochem.tuwien.ac.at
Asunto: [Wien] How to fit birch Murnaghan EOS for the orthorhombic case


Dear Delamora
Thank you for consideration of query.

 Sorry for late response because  my previous calculation was deleted as my system was crashed.

Now I re-optimised my orthorhombic structure with option 6 in "x optimize".

I generated 10 structure files and calculation finished without any issue.

Now I followed your suggestion and tried to fir "D 2nd degree equation" but could not do it.

I tried with different commands but each time I face a new problem.
I invoke the parabolfit_lapw command at terminal and then issue orders of dimension. See below what I am getting for different dimension orders:

A.# parabolfit_lapw
 enter dimensionality (2-4) of fit:
2
ls: No match.
ls: No match.
pmo_opt6.ene and pmo_opt6.latparam generated
 Enter dimension of fit (number of variable lattice parameters, 1-6):
           2  fitcase           6  parameter
 lowest data point:  0.000000000000000E+000  0.000000000000000E+000
  0.000000000000000E+000

 INCONSISTENT DIMENSIONS
 Parabolic equation of state:         info          66
 E = x1 + x2(a-x3)^2
        + x4(b-x5)^2 + x6(a-x3)(b-x5)
Fitparameter are
          1.000000          0.100000          0.000000          0.100000

          0.000000          0.100000
           0
         lattic parameters       energy         de(EOS)
                  Sigma:          0.000000
 Optionally create data points from fit function
 Enter number of datapoints for your           2 dimensional Energy surface
 NI=0 terminates; NI=1 will use 1 specific value in I-th component and allows to
  generate 2D-cuts
0.0u 0.0s 0:00.03 66.6% 0+0k 120+8io 1pf+0w
kcbhamu at Lenovo-B570:~/wien_ work/sabir/MP/pmo

B.  # parabolfit_lapw
enter dimensionality (2-4) of fit:
3
scf: Undefined variable.

C. # parabolfit_lapw
enter dimensionality (2-4) of fit:
4
ls: No match.
ls: No match.
pmo_opt6.ene and pmo_opt6.latparam generated
 Enter dimension of fit (number of variable lattice parameters, 1-6):
           4  fitcase          15  parameter
 lowest data point:  0.000000000000000E+000  0.000000000000000E+000
  0.000000000000000E+000  0.000000000000000E+000  0.000000000000000E+000

 INCONSISTENT DIMENSIONS
 Parabolic equation of state:         info          66
 E = x1 + x2(a-x3)^2
        + x4(b-x5)^2 + x6(a-x3)(b-x5)
        + x7(c-x8)^2 + x9(a-x3)(c-x8) + x10(b-x5)(c-x8)
        + x11(d-x12)^2 + x13(a-x3)(d-x12) + x14(b-x5)(d-x12) + x15(c-x8)(d-x12)
Fitparameter are
          1.000000          0.100000          0.000000          0.100000

          0.000000          0.100000          0.100000          0.000000

          0.100000          0.100000          0.100000          0.000000

          0.100000          0.100000          0.100000
           0
         lattic parameters       energy         de(EOS)
                  Sigma:          0.000000
 Optionally create data points from fit function
 Enter number of datapoints for your           4 dimensional Energy surface
 NI=0 terminates; NI=1 will use 1 specific value in I-th component and allows to
  generate 2D-cuts
0.0u 0.0s 0:00.01 0.0% 0+0k 0+8io 0pf+0w


I also saw one suggestion from Dr. Fecher but I could not implant it:

http://www.mail-archive.com/ wien at zeus.theochem.tuwien.ac. at/msg03070.html<http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg03070.html>
<http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg03070.html>

I do not know what more information I should supply here.

Could you please suggest me in some more detail?


I have the following scf file:
case_opt6_1.scf  case_opt6_5.scf                  case_opt6_abc___2.0_default. scf  case_opt6_abc___6.0_default. scf
case_opt6_2.scf  case_opt6_6.scf                  case_opt6_abc___3.0_default. scf  case_opt6_abc___7.0_default. scf
case_opt6_3.scf  case_opt6_abc__10.0_default. scf  case_opt6_abc___4.0_default. scf  case_opt6_abc___8.0_default. scf
case_opt6_4.scf  case_opt6_abc___1.0_default. scf  case_opt6_abc___5.0_default. scf  case_opt6_abc___9.0_default. scf

Regards
[http://mail.yimg.com/us.yimg.com/i/mesg/tsmileys2/01.gif]
________________________________

More information about the Wien mailing list