J. Appl. Phys. 127, 144101 (2020); https://doi.org/10.1063/1.5143243 127, 144101 © 2020 Author(s). Topology of the polarization field in PbTiO 3 nanoparticles of different shapes by atomic- level simulations Cite as: J. Appl. Phys. 127, 144101 (2020); https://doi.org/10.1063/1.5143243 Submitted: 23 December 2019 . Accepted: 23 March 2020 . Published Online: 09 April 2020 F. Di Rino, M. Sepliarsky , and M. G. Stachiotti