[QE-users] Makov-Payne Correction During Geometry Optimizations

[Dyer, Brock]

Hi all,

    I've been looking some non-periodic systems lately, and as such have been using the Makov-Payne correction to both correct for the dipole moment of my molecules, but also because I occasionally am dealing with charged systems and need to correct for the vacuum level shift. My main question as of right now is regarding the use of the Makov-Payne corrected energies while running relax calculations.

From the original Makov-Payne paper, when the lowest non-vanishing multipole is a quadrupole, the electrostatic potential is constant at all points in the unit cell, and therefore does not affect the forces on the ions and electrons in the cell.

However, in the case of the lowest non-vanishing multipole being a dipole, there should be a contribution from the dipole field on the forces. The Makov-Payne paper seems to imply that the convergence of the forces will be affected by the dipolar term, however it also notes that the dipoles in a cubic lattice do not interact. I am unsure if this means that there is no influence of the dipole on the forces in a cubic lattice, or if there is an influence of the dipole forces on the ions, but that the dipoles do not alter each other in a cubic lattice, i.e. there are no dipole-induced dipoles.

I know from running a few sample calculations that the Makov-Payne correction in Quantum ESPRESSO does not influence the forces, which I could tell by a comparison of the forces from a calculation with the correction and one without, all else being the same.

If it is the case that the dipole affects the ions, should the Makov-Payne correction not be applied in some manner to the forces, and if so, how can I try to test that?

Thanks,

Brock Dyer, Class of 2025


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