Dipole moment for periodic system

[UtpalLab123]

Dear Sir,
I am encountering a problem calculating the dipole moment for a periodic 2D system, such as twin-graphene. Using the electron density difference HDF5 file, I have successfully calculated the dipole moment for H₂O, NH₃, and HF, with values that exactly match the literature. However, when applying the same code to the periodic system, such as twin-graphene, it shows an intrinsic dipole moment instead of the expected zero dipole moment

[Anders Blom]

Are you talking about the out-of-plane dipole moment? That cannot be computed with the method you refer to, but perhaps https://www.sciencedirect.com/science/article/abs/pii/S0169433222026915 is helpful.

[UtpalLab123]

Yes, Sir, I am talking about the out of plane dipole moment. Sir, is there any way to calculate the out of plane dipole moment for a periodic system?

[sukhito teh]

From what I know, the dipole moment can be approximated using equation 7 in this paper https://journals.aps.org/prb/abstract/10.1103/PhysRevB.68.195408 . Another method  is to build a 3D configuration with "2D polarization configuration" (I don't know how to put in words, but you can check the supplementary information in this paper https://iopscience.iop.org/article/10.1088/1361-648X/ab1d0f )

[Anders Blom]

I think those "dipole moments" are a bit different. For the 2D Janus TMDs, I believe the method is as simple as computing the net charge transfer between the two layers and multiplying with the distance between the layers. Granted, you need a clear definition of the "distance", but I imagine the distance between the metal atoms is a reasonable choice.

DOI:10.1039/C7TC05225A
DOI:10.1016/j.cplett.2021.138495
DOI:10.1016/j.apsusc.2022.155163