The present study revisits the lattice stability of pure Cr in BCC, FCC, and HCP structures using ab initio calculations with PBE and ${\mathrm{r}}^2\mathrm{SCAN}$ functionals. A key advance is that ${\mathrm{r}}^2\mathrm{SCAN}$ directly captures stable antiferromagnetic (AFM) states at equilibrium volume without auxiliary techniques such as warm-start calculations (WSCs), while PBE often fails to maintain magnetic order. In addition, phonon calculations show that AFM configurations eliminate imaginary modes in FCC and HCP Cr, enabling reliable quasi-harmonic free-energy evaluations. The resulting temperature-dependent lattice stabilities agree markedly better with SGTE/CALPHAD values. Finally, the analysis of Cr-X $(X=\mathrm{Fe}, \mathrm{Ni}, \mathrm{Co})$ FCC solid solutions reveals characteristic local distortions and AFM spin arrangements on Cr sites in Cr-rich phases. Using relaxed AFM FCC-Cr as the end-member reference significantly improves agreement between ab initio mixing and formation enthalpies and CALPHAD assessments, indicating that AFM-based lattice stabilities of Cr should be adopted as the physically consistent reference for thermodynamic modeling.

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• Equations of state
• Thermodynamics
• Transition metals
• Density functional calculations