I am running calculations for charged molecules in siesta in cubic cell and figure out that Siesta can deal with charge system by adding tot_charge on the system. But I also want to add Makov-Payne correction for compensating the background charge with this additional charge. Is there any ways to use this in Siesta calculation.
In SIESTA you can set the NetCharge parameter to change the total net charge of the system. SIESTA adds a compensating uniform charge background to avoid divergence of the Coulomb energy.
Moreover, for molecules in a cubic cell SIESTA applies the Madelung correction to the energy to make converge faster with the size of the cell; Please check the https://siesta-project.github.io/bsc2017/siesta-4.1.pdf, flag NetCharge.
I tried to add Madelung correction in Siesta for the charged system but the overall correction effect does not seem to be perfect. I tried to calculate ionization energy with OH and C with this correction but the results are far away from the reference values.
Can anyone help with this? I am attaching the fdf file and suggest to me if I have to add anything extra in the INPUT.fdf.
1 8 O
2 1 H
#LatticeConstant 10.0 Ang
LatticeConstant 25.0 Ang
1.000000 1.000000 1.000000 90.0000 90.0000 90.0000
O 5.10000000 5.10000000 5.08423541 1
H 5.10000000 5.10000000 4.11576459 2
PAO.EnergyShift 0.001 Ry
MD.MaxForceTol 0.01 eV/Ang
MD.MaxCGDispl 0.100 Bohr
NetCharge = -1
xc.functional GGA # Exchange-correlation functional
MeshCutoff 300.0 Ry