[Wien] optimization of an orthorhombic cell

[Fecher, Gerhard]

you have three quantities V=a*b*c, b=a*(b/a) and c=a*(c/a)
so what is the problem ?

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 Dr. K. C. Bhamu [kcbhamu85 at gmail.com]
Gesendet: Freitag, 13. Oktober 2017 00:42
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] optimization of an orthorhombic cell

Dear List,


Could you please help me to get optimize lattice parameters from the procedure that I followed as mentioned below:



The procedure is a four-step task what I am following:

The original lattice parameters were: a, b, c=16.763005, 24.803600, 16.320431  >> vol 6785.64777697697 bohr^3.


1.   VARY C/A RATIO with CONSTANT VOLUME and B/A (orthorh lattice)

getting below optimized data:
 ==========================================================
Lowest point on X-axis is =  -1.615800
Minimum value of B/A is =     1.455755
Minimum value of ENE is =   -339059.104498 Ry
 ==========================================================
Value of A is =     16.85428 bohr  ;    8.91890 Ang
Value of B is =     24.53569 bohr  ;   12.98373 Ang
Value of C is =     16.40929 bohr  ;    8.68342 Ang
 ==========================================================
Initial value of  B/A is =          1.479663
Conv. Unit Cell Vol =  6785.7557 bohr^3 ; **********Ang^


2.  Volume optimization using option 1 in "x optimize" and then calculating new volume from eplot option.


Query: Step two is giving optimized volume but I do not know how to calculate lattices parameters from a single volume
value for the next step "VARY C/A RATIO with CONSTANT VOLUME and B/A (orthorh lattice)"?


The original cell volume and lattice parameters are mentioned at the beginning.

and the new volume from step two is: 6815.3427 bohr^3



The above same query is for the remaining process:

3. optimization of C/A

4. optimization of V.


*5 At the final step I will do structural relaxation (min_.....).


Could you please advice me how to proceed?



Kind regards,
Bhamu





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