Electronic band structure and Fermi surface of new 3.7 K superconductor LiCu2P2 from first-principles calculations

Research highlights: → New ThCr2Si2-like 3.7 K superconductor LiCu2P2 was recently discovered. → Electronic structure and Fermi surface of this phase were examined by FLAPW-GGA. → We found that LiCu2P2 may be classified as a (p + d) metal. → The Fermi surface of LiCu2P2 contains disconnected electronic- and hole-like pockets. → The bonding for LiCu2P2 is highly anisotropic and includes mixed covalent-ionic bonds. - Abstract: By means of the first-principles calculations, we have studied the structural, electronic properties and the Fermi surface (FS) of the newly discovered ThCr2Si2-like iron- and arsenic-free 3.7 K superconductor LiCu2P2. Our studies showed that LiCu2P2 is an unusual 'intermediate' system, which may be classified as a (p + d) metal, unlike the majority of 122 phases, which are d or sp metals. Unlike FeAs 122 phases having a typical cylinder-like (2D) FS topology, the Fermi surface of LiCu2P2 adopts a 3D-like two-sheet topology formed by disconnected electronic-like and hole-like pockets. The picture of inter-atomic bonding for LiCu2P2 is highly anisotropic and includes mixed covalent-ionic bonds Cu-P (inside [Cu2P2] blocks), direct P-P bonds (between the adjacent [Cu2P2] blocks) together with ionic bonds owing to Li → [Cu2P2] charge transfer.