Optimization of hexagonal and tetragonal structures using the 2Doptimize package of Jamal Morteza

The 2Doptimize package is developed by Jamal Morteza to optimize the hexagonal and tetragonal structures.

The package allows to optimize the volume and the c/a ratio.

 To download the guide click on the link below:

http://www.wien2k.at/reg_user/textbooks/2Doptimize.pdf

We will test the example used in the guide: Mg

Execution:

 

- Create the Mg.struct file and copy the following information in it

 

 

 Mg                                                         
H   LATTICE,NONEQUIV.ATOMS:  1 194_P63/mmc                  
MODE OF CALC=RELA unit=bohr
  6.066023  6.066023  9.851222 90.000000 90.000000120.000000
ATOM  -1: X=0.33333333 Y=0.66666667 Z=0.75000000
          MULT= 2          ISPLIT= 8
ATOM  -1:X= 0.66666667 Y=0.33333333 Z=0.25000000
Mg         NPT=  781  R0=0.00010000 RMT=    2.5000   Z: 12.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
   0      NUMBER OF SYMMETRY OPERATIONS

Select R_Kmax = 8 , L_max = 9, XC = pbe,and nkpoint = 3000
 
Select order of fit 5 and default parameters for volume and c/a changes.
 
Since Mg is not spin-polarized system, it is not necessary to modify Doptimize.job
file and you can run it.
 
After running 2Doptimize.job file and ana2D_lapw, you will find the below values
in Terminal and Mg.outputeos file.

 

Procedure:

- list the working repertory

username@machinename:~/Mg$ ls
 Mg.struct

- run the command ""init_lapw"

username@machinename:~/Mg$ init_lapw ---> normal initialization

 

NB: It's preferable to create a session and do the initialization in the w2web interface and do the following in terminal.

- Execute the command " set2D_lapw"

username@machinename:~/Mg$ set2D_lapw ---> to setup the calculation
  
accept the default values

 

-  Modify the script 2Doptimize.job according to your needs ----> this time don't modify

- Run the script

username@machinename:~/Mg$ 2Doptimize.job --->
( the SCF calculation is running for the different structures : it takes much time)

- Execute the command "ana2D_lapw"

username@machinename:~/Mg$ ana2D_lapw ---> to analyse the results

( accepts the default values and reply by yes )

The results are in the file   Mg.outputeos

 Equation of state: EOS2 (PRB52,8064)        info           7
 a,b,c,d      -798.113831        24.000954      -314.314396      1037.976992
 V0,B(GPa),BP,E0       291.9146        39.4517         4.0088

 Equation of state: Murnaghan                info           7
 E=E0+[B*V/BP*(1/(BP-1)*(V0/V)**BP +1)-B*V0/(BP-1)]/14703.6
 Pressure=B/BP*((V0/V)**BP -1)
 V0,B(GPa),BP,E0       291.8967        39.7076         4.3367       -798.082679
         vol       energy         de(EOS2)      de(Murnaghan)  Pressure(GPa)
     282.5344     -798.082250     0.000001     0.000001          1.390
     298.2308     -798.082496    -0.000003    -0.000004         -0.814
     313.9271     -798.080709     0.000005     0.000007         -2.478
     329.6235     -798.077343    -0.000004    -0.000005         -3.751
     345.3198     -798.072796     0.000001     0.000001         -4.739
                  Sigma:          0.000003     0.000004

 Equation of state: Birch-Murnaghan                info           7
 E = E0 + 9/16*(B/14703.6)*V0*[(eta**2-1)**3*BP + (eta**2-1)**2*(6-4*eta**2)]
        --> eta = (V0/V)**(1/3)
 Pressure = 3/2*B*(eta**7 - eta**5)*(1 + 3/4*(BP-4)*[eta**2 - 1])
 V0,B(GPa),BP,E0       291.9128        39.4672         4.0326       -798.082676
         vol       energy         de(Birch-Murnaghan)  Pressure(GPa)
     282.5344     -798.082250     0.000001                1.377
     298.2308     -798.082496    -0.000003               -0.809
     313.9271     -798.080709     0.000005               -2.479
     329.6235     -798.077343    -0.000004               -3.755
     345.3198     -798.072796     0.000001               -4.729
                  Sigma:          0.000003

In Terminal:

 #####################################
Vol-opt= 309.5921 ,  coa-opt= 1.6295

a0= 6.03117 , c0= 9.82779 bohr
a0= 3.1915 , c0= 5.2006 Ang

##################################### 

You may find the optimal values for the lattice paramets for different fit orders in the file "fitorder".

 #####################################
Order of fit 3
a0= 6.03240 , c0= 9.82376 bohr
a0= 3.1922 , c0= 5.1985 Ang

#####################################
Order of fit 4
a0= 6.03265 , c0= 9.82296 bohr
a0= 3.1923 , c0= 5.1980 Ang

#####################################
Order of fit 5
a0= 6.03117 , c0= 9.82779 bohr
a0= 3.1915 , c0= 5.2006 Ang

#####################################