A comment on "Different STM Images of the Superstructure on a Clean Si(133)-6x2 Surface" (JETP Letters 105 (8), 477-483 (2017)).

In the recent paper by Teys [JETP Letters 105 (8), 477-483 (2017)], an atomic model for the Si(331) reconstructed surface (hereby referred to as T-model) was proposed on the basis of high-resolution scanning tunneling microscopy (STM) images. While detailing the virtues against previous and abandoned models, the author avoids any reference to the rather distinct 8P-model advocated few weeks earlier by Zhachuk and Teys [R. Zhachuk, S. Teys, Phys. Rev. B 95, 041412 (2017)], casting doubts to his own work. Formulated that way, findings from Ref. [JETP Letters 105 (8), 477-483 (2017)] leave readers of JETP Letters with a partial and confusing view of the problem, and above all, leaves the observations open to ambiguous interpretation. The 8P-model is also based on STM measurements, and unlike the T-model, passed through the scrutiny of first-principles calculations. The present comment reconciles Ref. [JETP Letters 105 (8), 477-483 (2017)] with the literature by supplementing the discussion with a missing and critical account on the stability and electronic structure of the T- versus 8P-models of Si(331).