This paper presents a study on the electronic structure of Mn-based Heusler alloys with the Clb crystal structure (MgAgAs type), specifically NiMnSb. Using the augmented-spherical-wave method, the authors calculated the band structure and found that these materials exhibit unique electronic properties. The majority-spin electrons are metallic, while the minority-spin electrons are semiconducting, leading to 100% spin polarization of the conduction electrons at the Fermi level. This is a novel feature, as it implies that all conduction electrons in these materials are spin-polarized. The study shows that the Clb structure leads to an asymmetric band structure, with the minority-spin electrons forming a semiconductor gap and the majority-spin electrons forming continuous bands. This is due to the broken inversion symmetry in the Clb structure, which results in a different point symmetry for the Mn sites compared to the L21 structure. The authors also compare the electronic structure of Clb compounds with that of L21 Heusler alloys, finding similarities in the large Mn d-electron exchange splittings and the polarization of Mn d bands away from the Fermi level. The paper discusses the implications of these findings, including the potential for novel magnetic properties and the importance of the Clb structure in achieving the unique electronic behavior. The authors also mention that the results support the use of an itinerant-electron band model within the local-density formalism to describe the magnetic properties of Heusler materials. The study concludes that the existence of a gap in the minority-spin bands is a striking feature of these materials and that the results are consistent with experimental data.This paper presents a study on the electronic structure of Mn-based Heusler alloys with the Clb crystal structure (MgAgAs type), specifically NiMnSb. Using the augmented-spherical-wave method, the authors calculated the band structure and found that these materials exhibit unique electronic properties. The majority-spin electrons are metallic, while the minority-spin electrons are semiconducting, leading to 100% spin polarization of the conduction electrons at the Fermi level. This is a novel feature, as it implies that all conduction electrons in these materials are spin-polarized. The study shows that the Clb structure leads to an asymmetric band structure, with the minority-spin electrons forming a semiconductor gap and the majority-spin electrons forming continuous bands. This is due to the broken inversion symmetry in the Clb structure, which results in a different point symmetry for the Mn sites compared to the L21 structure. The authors also compare the electronic structure of Clb compounds with that of L21 Heusler alloys, finding similarities in the large Mn d-electron exchange splittings and the polarization of Mn d bands away from the Fermi level. The paper discusses the implications of these findings, including the potential for novel magnetic properties and the importance of the Clb structure in achieving the unique electronic behavior. The authors also mention that the results support the use of an itinerant-electron band model within the local-density formalism to describe the magnetic properties of Heusler materials. The study concludes that the existence of a gap in the minority-spin bands is a striking feature of these materials and that the results are consistent with experimental data.