regular surface

https://doi.org/10.1351/goldbook.14082
Perfect surface of a solid without heterogeneity or defect.
Note: Rigorously speaking, this is a theoretical notion. In practice, however, this term is used to refer to local space regions of real relaxed and reconstructed surfaces if the perturbations caused by the nearest adjacent (surface) defects can be neglected.
Source:
PAC, 2011, 83, 931. (Glossary of terms used in photocatalysis and radiation catalysis (IUPAC Recommendations 2011)) on page 986 [Terms] [Paper]