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[ilyes.hamdi@fst.rnu.tn]

Dear Abinit users
I'm trying the optimization of CrO2(semi-metal)in rutile structure, i get 
problem with convergence of Etot when iscf=5, i change it to 3 and done many 
convergence study with respect to kpts, ecut and tsmear. Following the paper 
of Steven P. Lewis et al. Phys rev B55, 10253(1997) the experimental values 
of a, c and intenal parameter u are 4.419 A, 2.912 A and 0.303 . Optimization 
after 12 BFGS iteration gives 4.44A, 2.93 A ,0.303 and a pressure of order 
10-5 Gpa , and a Magnetisation (Bohr magneton)=  4.01, but when i done a scf 
calculation with these values, i get a pressure of order 10+2 Gpa and 
6.13899687E-09 (Bohr magneton). Any coments would be very helpfull on this 
difference between the pressures of the two calculations.
following is my input and a part of the output(SCF calculation).
------------------------------------------
# Crystalline CrO2 : SCF calculation in rutile struc.
#Definition of the  unit cell

acell  2*4.44 2.93 angstr        
rprim  1.0 0.0 0.0    
       0.0  1.0 0.0   
       0.0  0.0  1.0

#Definition of the atom types
ntypat 2           
znucl 24 8      
                           

#Definition of the atoms
natom 6           
typat 1 1 2 2 2 2      
xred              
                  
  0.0 0.0 0.0    
  1/2 1/2 1/2     
  0.303 0.303 0   
  0.697 0.697 0   
  0.803 0.197 0.5
  0.197 0.803 0.5

#Definition of the planewave basis set
ecut 41       


#Definition of the k-point grid
kptopt 1          
ngkpt 3 3 6                                    
nshiftk 1         
shiftk  0.5 0.5 0.5 
 
#Definition of the band structure
nsppol 2
occopt  3
nband 24
tsmear 0.01

#Definition of the SCF procedure
nstep 200          
tolvrs 1.0d-08    
nline  7    
iscf   3 
diemac  1.0d6   
*****************************************************
some of output:
**************************************************


     iter   Etot(hartree)     deltaE(h) residm    vres2   diffor   maxfor   
magn
 ETOT  1  -67.247739840416    -6.72E+01 2.49E-02 9.48E+04 1.4E-01 1.44E-01 
0.000
 ETOT  2  -68.955544632943    -1.71E+00 5.60E-02 1.25E+05 3.7E-01 2.26E-01 
0.000
 ETOT  3  -78.952454147472    -1.00E+01 5.05E-02 3.23E+04 1.4E-01 8.51E-02 
0.000
 ETOT  4  -63.140986093472     1.58E+01 2.45E-01 1.20E+05 2.3E-01 1.44E-01 
0.000
 ETOT  5  -81.869772587910    -1.87E+01 1.60E-01 7.65E+03 2.0E-01 5.49E-02 
0.000
 ETOT  6  -83.076701443028    -1.21E+00 1.20E-01 1.31E+03 3.8E-02 1.70E-02 
0.000
 ETOT  7  -83.222377703227    -1.46E-01 1.14E-02 5.49E+02 1.6E-02 5.37E-04 
0.000
 ETOT  8  -83.309899162123    -8.75E-02 3.97E-03 8.58E+00 4.4E-03 4.96E-03 
0.000
 ETOT  9  -83.311340099561    -1.44E-03 5.47E-04 4.45E-01 4.3E-03 6.56E-04 
0.000
 ETOT 10  -83.311407885475    -6.78E-05 1.07E-03 1.42E-01 7.2E-04 1.38E-03 
0.000
 ETOT 11  -83.311438573177    -3.07E-05 3.88E-03 1.78E-03 3.3E-04 1.05E-03 
0.000
 ETOT 12  -83.311438940661    -3.67E-07 8.88E-04 3.18E-04 6.2E-05 9.87E-04 
0.000
 ETOT 13  -83.311438981139    -4.05E-08 1.76E-03 9.51E-05 2.6E-05 9.61E-04 
0.000
 ETOT 14  -83.311438995664    -1.45E-08 1.41E-03 2.52E-05 4.8E-06 9.66E-04 
0.000
 ETOT 15  -83.311439000529    -4.86E-09 1.92E-03 2.56E-06 7.4E-06 9.58E-04 
0.000
 ETOT 16  -83.311439001698    -1.17E-09 2.40E-03 3.53E-07 1.2E-07 9.59E-04 
0.000
 ETOT 17  -83.311439002418    -7.20E-10 1.13E-03 4.85E-08 7.8E-07 9.58E-04 
0.000
 ETOT 18  -83.311439002934    -5.16E-10 9.01E-04 1.63E-08 1.5E-08 9.58E-04 
0.000
 ETOT 19  -83.311439003245    -3.12E-10 2.73E-04 1.54E-09 1.7E-07 9.58E-04 
0.000

 At SCF step   19       vres2   =  1.54E-09 < tolvrs=  1.00E-08 =>converged.
    .
    .
    .
    .
frms,max,avg= 3.2830138E-02 4.9245207E-02   0.000E+00  0.000E+00  0.000E+00 
e/A
 length scales=  8.390384034610  8.390384034610  5.536897572389 bohr
              =  4.440000000000  4.440000000000  2.930000000000 angstroms
 Fermi energy (hartree) =   0.21252
 Magnetisation (Bohr magneton)=  6.13899687E-09
 Total spin up =  1.80000000E+01   Total spin down =  1.80000000E+01
  .
  .
  .
  .
  .
 
 
--------------------------------------------------------------------------------
 Components of total free energy (in Hartree) :

    Kinetic energy  = 7.84037734506521E+01
    Hartree energy  = 1.74607103192631E+01
    XC energy       =-1.84647917827223E+01
    Ewald energy    =-7.28612822727410E+01
    PspCore energy  = 3.05749299430425E+00
    Loc. psp. energy=-7.72168758846552E+01
    NL   psp  energy=-1.36401206375395E+01
    >>>>> Internal E=-8.32610938134387E+01

    -kT*entropy     =-5.03451898067908E-02
    >>>>>>>>> Etotal=-8.33114390032455E+01

 Other information on the energy :
    Total energy(eV)=-2.26701950832303E+03 ; Band energy (Ha)= 
-1.7300399531E+00
--------------------------------------------------------------------------------

 Cartesian components of stress tensor (hartree/bohr^3)
  sigma(1 1)=  3.55389651E-03  sigma(3 2)=  0.00000000E+00
  sigma(2 2)=  3.55389651E-03  sigma(3 1)=  0.00000000E+00
  sigma(3 3)=  4.03266316E-03  sigma(2 1)=  0.00000000E+00

-Cartesian components of stress tensor (GPa)         [Pressure= -1.0925E+02 
GPa]
- sigma(1 1)=  1.04559224E+02  sigma(3 2)=  0.00000000E+00
- sigma(2 2)=  1.04559224E+02  sigma(3 1)=  0.00000000E+00
- sigma(3 3)=  1.18645023E+02  sigma(2 1)=  0.00000000E+00