Examination of magnetic perovskite oxides ATO$_3$ containing 3d-transition-metals has led to novel and functional compounds for many applications. Here, in this paper, we present detailed computations based on firstprinciples density functional theory (DFT) of the crystal, thermodynamic, magnetic and electronic structures of SrTO$_3$ (T = V, Cr, Mn, Co). Full potential linear muffin-tin orbital (FP-LMTO) method through the Perdew-Wang generalized gradient approximation (PW91-GGA) has been utilized in all computations. In addition, the effects of exchange-correlation energy (U) and spin-orbit (SO) coupling on magnetic and electronic structures have been investigated via(GGA+SO), (GGA+U) and (GGA+SO+U) methods. The computational results of crystal and thermodynamic structures revealed that all SrTO$_3$ stabilize in a cubic symmetry with (a${\approx}$3.80 A° ; space group Pm-3m). Besides, SrTO$_3$ compounds show ferromagnetic (FM) and metallic features, which transform to FM and half-metallic (HM) when U energy and SO coupling are included with GGA, except for (T = Co) that remains in its FM metallic nature. These parameters enhance the total density of states (DOS), partial DOSs and magnetic moments, and all obtained DFT results are in excellent agreement with the experimental data. Thus, the exciting HM–FM nature and stable crystal structures make SrTO$_3$ aseffective, promising and candidate material for modern spintronic applications.

Generalized gradient approximation (GGA) computations based on the first-principles density functional theory (DFT) are executed to gain insight into the structural stability and physical properties of the 3d-transition-metalbased praseodymium series of perovskite compounds PrTO$_3$. Correspondingly, to investigate the effect of on-site Coulomb repulsion energy, the exchange-correlation version of GGA is implemented via utilizing the (GGA+U) functional.The computed ground state energies ($E_0$) and equilibrium structural parameters of the varied T-site [T = Sc, Ti, V, Cr, Mn, Fe, Co] in the unit cell of PrTO$_3$ reveal a cubic symmetry (Pm-3m) in all compounds, in a good match with the fewexisting DFT and experimental literature. Besides, the computed spin-polarized band structures and partial and total density of states (DOS) within GGA predict a half-metallic (HM) behaviour for [T = Sc] perovskite and a metallic naturefor the rest [T = Ti, V, Cr, Mn, Fe, Co]. The analysis of E0 results, DOSs and spin magnetic moments indicates that all perovskites PrTO$_3$ are stable in a ferromagnetic (FM) phase via the double exchange interaction T$^{3+}$–O$^{2-}$–T$^{4+}$. PrTO$_3$ show FM order with fractional values of their total spin magnetic moment per unit cell ($M_{PrTO{_3}}$ ), except [T = Sc] perovskite that gives integer value ($M_{PrScO{_3}}$ ${\approx}$ 2.0 ${\mu}_B$) with HM-FM property. Conversely, it is found that PrTO$_3$ exhibit HM-FM properties when [T = Sc, V, Cr, Mn, Fe] plus GGA?U is applied. Due to the cation–anion hybridizations, Pr$^{3+}$–O$^{2–}$ and T$^{3+}$–O$^{2–}$, both Pr$^{3+}$ and T$^{3+}$ ions contribute to the largest part of $M_{PrTO{_3}}$ with minor effects coming from O$^{2–}$ ions and interstitials. Furthermore, the three-dimensional and two-dimensional electronic charge density plots of PrTO$_3$ along the (110) plane confirm strong ionic nature along the Pr$^{3+}$–O$^{2–}$ bonds, whereas the other O$^{2–}$–T$^{3+}$–O$^{2–}$ bondshave strong covalent character.