Generalized gradient approximations Calculations 3 Density functional theory 3 Energy gap 3 Electric conductivity 2 Electrical conductivity 2 Electronic structure 2 Electronic structure and optical properties 2 First-principles 2 Structural properties 2 Ab initio calculations 1 Absorption spectroscopy 1 Band structure 1 Ca-doped α-Ga2O3 1 Calcium 1 Calculated optical properties 1 Charge density distributions 1 Chemical bonds 1 Cobalt compounds 1 Comparatives studies 1 Complex dielectric functions 1 Crystal structure 1 Debye temperature 1 Density of states 1 Density-functional-theory 1 Electrical and optical properties 1 Electrodes 1 Electronic properties 1 Environmental technology 1 Exchange-correlation potential 1