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[Damien Caliste <damien.caliste@cea.fr>]

Hello,

Le 20/03/2008, nathaniel.deskins@pnl.gov a écrit :
> I've modeled this reaction with other planewave and gaussian codes.
> The energy for the reaction varies between 4.1-5.1 eV (depending on
> basis set and potential) while the Ti-Cl distance is near 2.22-2.23
> angstroms. All this was with PBE XC functional. 
I've tested your input files within a wavelet basis set (that have the
same property as plane waves to be as precise as possible) and I obtain
results similar to the one you have with gaussians basis sets.

Here are the results:
hgrid crmult bond-length  binding-energy
0.5   4      2.130        -7.7589
0.45  4.5    2.208        -7.3101
0.4   5      2.218        -4.5927 
0.35  5.5    2.222        -4.5429
0.3   6      2.222        -4.5218

TiCl total energy
 -18.479037693
 -18.488242138
 -18.494410365
 -18.496620706
 -18.497434335

Ti total energy
 -3.3109492793
 -3.3210559183
 -3.4213936690
 -3.4232515518
 -3.4240442088

Cl total energy
 -14.882951551
 -14.898541633
 -14.904236391
 -14.906420534
 -14.907213698

Where hgrid is in bohr and gives the precision of the basis set and
crmult gives the spatial expansion (as a multiplying factor), see
Abinit 5.5 documentation for wvl_crmult.

I've also attached the input files I used. The results for low
precision hgrid (> 0.4 bohr) can be discussed especially because the
DIIS goes to an excited states and because the spatial expansion is
too small, but this requires further investigations, I only give quick
and direct results. For better hgrid values (the lower, the better),
results can be trusted and are good.

Damien.


PS: the ti file is given with an equivalent occupation for the
degenerated states but above results are for asymmetric occupation, to
have them, change occ to 1111 instead of 111 1/3 1/3 1/3.
PPS: the 5 datasets of complete geometry relaxation have taken 40
minutes on 4 CPU with less than 400Mo per proc for the finer mesh
(equivalent to Ec=220Ht in the finer zones).
acell 25 25 25    # The keyword "acell" refers to the
ntypat 1          # There is only one type of atom
znucl 17           # The keyword "znucl" refers to the atomic number of the 
natom 1           # There are two atoms
typat 1          # They both are of type 1, that is, Hydrogen
xcart             # This keyword indicates that the location of the atoms
   0.0 0.0 0.0    # Triplet giving the cartesian coordinates of atom 1, in 
Bohr
ecut 15.0         # Maximal plane-wave kinetic energy cut-off, in Hartree
nkpt 1            # Only one k point is needed for isolated system,
nsppol 2
occopt 2
nband 4 4  
occ 1 1 1 1 
    1 1 1 0   
fixmom 1
spinat 0.0 0.0 1.0  # Initialisation of spin
nstep 50          # Maximal number of SCF cycles
toldfe 1.0d-6     # Will stop when, twice in a row, the difference 
diemac 2.0        # Although this is not mandatory, it is worth to

usewvl 1
icoulomb 1
optforces 0
optstress 0
iscf 2
nsym 1
nwfshist 5
ndtset 5
wvl_hgrid: 0.5
wvl_hgrid+ -0.05
wvl_crmult: 4
wvl_crmult+ 0.5

acell 25 25 25    # The keyword "acell" refers to the
ntypat 1          # There is only one type of atom
znucl 22           # The keyword "znucl" refers to the atomic number of the 
natom 1           # There are two atoms
typat 1          # They both are of type 1, that is, Hydrogen
xcart             # This keyword indicates that the location of the atoms
   0.0 0.0 0.0    # Triplet giving the cartesian coordinates of atom 1, in 
Bohr
ecut 15.0         # Maximal plane-wave kinetic energy cut-off, in Hartree
nkpt 1            # Only one k point is needed for isolated system,
nsppol 2
occopt 2
nband 6 6
occ 1 1 1 1/3 1/3 1/3 0 0 0 0 0 0
fixmom 4
spinat 0.0 0.0 4.0  # Initialisation of spin
nstep 50          # Maximal number of SCF cycles
tolwfr 1.0d-4     # Will stop when, twice in a row, the difference 
diemac 2.0        # Although this is not mandatory, it is worth to

usewvl 1
icoulomb 1
optforces 0
optstress 0
iscf 2
nsym 1
nwfshist 5
ndtset 5
wvl_hgrid: 0.5
wvl_hgrid+ -0.05
wvl_crmult: 4
wvl_crmult+ 0.5
acell 25 25 25    # The keyword "acell" refers to the
ntypat 2          # There is only one type of atom
znucl 22 17          # The keyword "znucl" refers to the atomic number of the 
natom 2           # There are two atoms
typat 1 2         # They both are of type 1, that is, Hydrogen
xcart             # This keyword indicates that the location of the atoms
   0.0 0.0 0.0    # Triplet giving the cartesian coordinates of atom 1, in 
Bohr
   4.3 0 0 
ecut 30.0         # Maximal plane-wave kinetic energy cut-off, in Hartree
nkpt 1            # Only one k point is needed for isolated system,
nsppol 2
occopt 2
nband 6 6
occ 1 1 1 1 1 1 1 1 1 1 1 0
fixmom 2
spinat 0.0 0.0 3.0  
       0.0 0.0 1.0
ionmov 2
tolmxf 5.0d-4
ntime 20
nstep 50          # Maximal number of SCF cycles
toldfe 1.0d-6     # Will stop when, twice in a row, the difference 
diemac 2.0        # Although this is not mandatory, it is worth to

usewvl 1
icoulomb 1
optstress 0
iscf 2
nsym 1
nwfshist 5
ndtset 5
wvl_hgrid: 0.5
wvl_hgrid+ -0.05
wvl_crmult: 4
wvl_crmult+ 0.5