3 -6 -4 -2 0 2 -1 0 1 PDOS (states e V $_{-1}$ atom-1 ) (d) O1 2 p O2 2 p PDOS (states eV $_{-1}$ atom-1 ) Energy (eV) -1 0 1 (c) Co  e$_{g}$ d$_{x}$ $^{2}$-y2 d$_{z}$ $^{2}$-r2 Co  t$_{2g}$ -1 0 1 (b) d$_{xz}$ / d$_{yz}$ d$_{xy}$ DOS (states eV $_{-1}$ fu-1 ) -10 -5 0 5 10 (a) TDOS -6 -4 -2 0 2 1 (d) O2 p$_{x}$ / p$_{y}$ p$_{z}$ PDOS (states eV -1  atom -1 ) Energy (eV) -6 -4 -2 0 2 1 (c) O1 Co  e$_{g}$ p$_{x}$ / p$_{y}$ p$_{z}$ -6 -4 -2 0 2 1 2 (b) PDOS (states eV -1  atom -1 ) d$_{x}$ $^{2}$-y2 d$_{z}$ $^{2}$-r2 -6 -4 -2 0 2 1 2 (a) Co  t$_{2g}$ d$_{xz}$ / d$_{yz}$ d$_{xy}$ FIG. 3: (Color online) The density of states obtained from ferromagnetic GGA calculation. (a) total density of states (TDOS), (b) d xz /d yz (thin lines) and d xy (thick lines) states, and (c) d$_{x}$ $^{2}$$_{−}$y2 (thin lines) and d$_{z}$ $^{2}$$_{−}$r2 (thick lines) states. In (d) partial density of p symmetric states for planar oxygen (O1) and apical oxygen (O2) are represented by thin and thick lines, respectively. FIG. 2: (Color online) The partial density of different symmetric states obtained from nonmagnetic solution. (a) d xz /d yz (thin lines) and d xy (thick lines) states, (b) d$_{x}$ $^{2}$$_{−}$y2 (thin lines) and d$_{z}$ $^{2}$$_{−}$r2 (thick lines) states. The p x /p y (thin lines) and p z (thick lines) symmetric partial density of states of planar oxygen (O1) and apical oxygen (O2) are shown in (c) and (d), respectively. In order to know the electronic and magnetic struc- tures of the compound we have carried out FM calcu- lation. The energy of the FM solution is found to be ∼ 336 meV less than that of nonmagnetic solution in- dicating the ferromagnetic ground state for the system. This result is in accordance with the experimental obser- vation and earlier theoretical calculations. 3,5 The total and partial density of states obtained for the FM config- uration are plotted in Fig. 3. There is an asymmetric distribution of states in both the spin channels. The dif- ference between number of electrons in up and down spin channels is a measure of net magnetization and found to be ∼ 2. Under the rigid band picture one can estimate the effective value of the exchange parameter ( J ) by con- sidering the energy difference between the up and down band edges, which is estimated to be ∼ 0.4 eV. The t$_{2}$$_{g}$ up-spin bands are fully occupied whereas t$_{2}$$_{g}$ down-spin and e$_{g}$ bands are partially occupied. Similar to the nonmagnetic case, e$_{g}$ bands are highly extended in comparison to t$_{2}$$_{g}$ bands. The strength of ex- change parameters for t$_{2}$$_{g}$ and e$_{g}$ electrons are estimated to be ∼ 0.6 and 0.4 eV, respectively. The larger value of J for t$_{2}$$_{g}$ electrons can be attributed to more localized t$_{2}$$_{g}$ states leading to higher Coulomb interaction. Inter- estingly, O 2 p PDOS also show spin polarization and the estimated value of J for p electrons is also found to be ∼ 0.4 eV. The values of magnetic moment for Co, O1 and O2 atoms are found to be about 1.52, 0.17 and 0.07 µ$_{B}$ , respectively. The total magnetization per formula unit is ∼ 2 µ$_{B}$ , which is almost same to the earlier reports. 3,5 The appearance of magnetic moments at the O sites may be attributed to the strong hybridization between d$_{x}$ $^{2}$− y 2 and O1 ( p$_{x}$ , p$_{y}$ ) orbitals; and d$_{z}$ $^{2}$− r 2 and O2 p$_{z}$ orbitals. The values of magnetic moment for O1 and O2 atoms also appear to support this conjecture as the magnetic moment of O1 is roughly 2 times larger than that of O2. In order to know the role of orbital degrees of free- dom on the magnetic properties of the system we have included SOC in the calculations by considering magneti- zation directions along (001) and (100) axes. Our calcu- lations indicate that the c -axis is an easy axis as the total energy of the system for (001) direction is found to be ∼ 2.7 meV/Co less than that for (100) direction. This result