The kernel of the study of magnetic quantum materials focuses on the magnetic phase transitions, among which the most common phenomenon is the transition between low-temperature magnetic-ordered phase to high-temperature paramagnetic phase. A paramount question is if such paramagnetic phase of the correlated solids can be well described by single-particle band theory to facilitate the experimental observations. In this work, we investigate the properties of temperature-driven paramagnetic phase via two different approaches within the framework of density functional theory, monomorphous and polymorphous description. From a comprehensive comparison of total energies, symmetries and band structures, we demonstrate the necessity for a proper treatment of paramagnetic phases with several prototypical examples. For Pauli paramagnetism phase, the vanishing of spin moments permits us to apply a nonmagnetic monomorphous description, while for paramagnetism with disordered local moments, such description imposes unrealistic high symmetry, leading to a metallic state in certain cases, inconsistent with the experimental observation. In contrast, the polymorphous description based on a large-enough supercell with disordered local moments is able to count in the effects of distinct local environments, such as symmetry lowing, providing a more reliable paramagnetic electronic structure and total energy compared with experiments. Our work shed new insights on discovering the temperature-dependent magnetic phase transition in the field of magnetic quantum materials.
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