EXPLORING CRYSTAL CHEMISTRY OF BINARY SILVER CHLORIDES WITH EVOLUTIONARY ALGORITHMS AND DENSITY FUNCTIONAL THEORY

Silver chloride, AgCl, is well known crystalline solid that has been mostly recognized due to its photoactive properties. Intriguingly, no other crystallize phase of silver with chlorine is known. This is quite surprising considering the richness of stoichiometries in other transition metal halides, the most frequent being di- and trichlorides. Additionally, Cu and Au that sits together with Ag in Group 11 form apart from mono- and dihalides also M₄Cl₈ and M₂Cl₆ phases. The lack of these crystalline phases in the Ag-Cl system is even more surprising since the binary system of silver fluorides is quite rich [1]. The absence of their chloride counterparts may indicate incompatibility of chlorine with higher oxidation states of silver, but this issue requires through examination. Employing evolutionary algorithms (EA) in combination with Density Functional Theory (DFT), we have recently uncovered chemical identity of metastable crystalline AgCl₂ phase [2]. Subsequently, computing simple DFT models of Cl-staffed/enriched cubic silver and vice versa, we have demonstrated possible existence of several other stoichiometries [3,4]. In this contribution we present their crystal and electronic structures and formation enthalpies as predicted by combined EA+DFT approach, while considering also the existence of chlorine substituted Ag_xF_y phases and possibility to stabilize them under external pressure. Our ongoing exhaustive computational study reveals very different crystal chemistry of silver chlorides in respect to fluorides involving polychloride anions.

Acknowledgement: The European Regional Development Fund, Research and Innovation Operational Programme, for project No. ITMS2014+: 313011W085; Scientific Grant Agency of the Slovak Republic, grant No. VG 1/0223/19; the Slovak Research and Development Agency, grant No. APVV-18-0168; Aurel supercomputing infrastructure in CC of Slovak Academy of Sciences acquired in projects ITMS 26230120002 and 26210120002 funded by ERDF.

References:

[1] T. Nakajima, B. Žemva and A. Tressaud (Editors), Elsevier Science S.A, (2000).

[2] M. Derzsi A. Grzelak, P. Kondratiuk, K.Tokár and W. Grochala, Crystals, 9, 423 (2019).

[3] M. Uhliar, Bachelor thesis 2019, available at https://opac.crzp.sk/ .

[4] M. Uhliar and M. Derzsi, 19^th Symposium on fluorine chemistry, Warsaw (2019).