3.6. Example: (CaTiO3)5

Tip

The sample input and output files can be found in testfiles/atom/4-catio35.

The system here is a cluster related to perovskite: \(\left(\mathrm{Ca}\mathrm{Ti}\mathrm{O}_3\right)_5\). We will use the Coulomb-Morse-Repulsion potential to model its interactions. The parameters can be found in misc/atomic-force-field.txt:

misc/atomic-force-field.txt

Metal-Metal        0.00        0.00           0.00        22.0         # J. Phys. Chem. B 2006, 110, 11780
O (-1.2)-O(-1.2)   0.042395    1.379316       3.618701    22.0         # J. Phys. Chem. B 2006, 110, 11780
...
Ca(+1.2)-O(-1.2)   0.030211    2.241334       2.923245    5.0          # J. Phys. Chem. B 2006, 110, 11780
Sr(+1.2)-O(-1.2)   0.019623    1.886000       3.328330    3.0          # J. Phys. Chem. B 2006, 110, 11780
Ba(+1.2)-O(-1.2)   0.065011    1.547596       3.393410    5.0          # J. Phys. Chem. B 2006, 110, 11780
Sc(+1.8)-O(-1.2)   0.000333    3.144445       3.200000    2.6          # J. Phys. Chem. B 2006, 110, 11780
Ti(+2.4)-O(-1.2)   0.024235    2.254703       2.708943    1.0          # J. Phys. Chem. B 2006, 110, 11780
Zr(+2.4)-O(-1.2)   0.206237    2.479675       2.436997    1.0          # J. Phys. Chem. B 2006, 110, 11780

Step 1: call abcinp to generate input files:

$ abcinp catio3 3 CoulombMorseRepulsion 10 100 1000 5 10 5 Ca 5 Ti 15 O
Parameters for atom 0: q > +1.2
Parameters for atom 1: q > +2.4
Parameters for atom 2: q > -1.2
Parameters for atom-pair 0-0: D alpha rho C > 0 0 0 22.0
Parameters for atom-pair 0-1: D alpha rho C > 0 0 0 22.0
Parameters for atom-pair 0-2: D alpha rho C > 0.030211 2.241334 2.923245 5.0
Parameters for atom-pair 1-1: D alpha rho C > 0 0 0 22.0
Parameters for atom-pair 1-2: D alpha rho C > 0.024235 2.254703 2.708943 1.0
Parameters for atom-pair 2-2: D alpha rho C > 0.042395 1.379316 3.618701 22.0

Step 2: Run the global optimization:

$ atom catio3.inp > catio3.out

After a few seconds, you will find the global minimum in catio3.xyz (see below) and local minima in catio3-LM.