  A comparative computational study of stability of candidate structures for an
as yet unknown silver dichloride AgCl2 is presented. It is found that all
considered candidates have a negative enthalpy of formation, but are unstable
towards charge transfer and decomposition into silver(I) chloride and chlorine
within the DFT and hybrid DFT approaches in the entire studied pressure range.
Within SCAN approach, several of the true AgIICl2 polymorphs (i.e. containing
Ag(II) species) exhibit a region of stability below ca. 20 GPa. However, their
stability with respect to aforementioned decomposition decreases with pressure
by account of all three DFT methods, which suggests a limited possibility of
high pressure synthesis of AgCl2. Some common patterns in pressure induced
structural transitions observed in the studied systems also emerge, which
further testify to an instability of hypothetical AgCl2 towards charge transfer
and phase separation.
