Compressed Sr superconducting transition temperature up to 17.65 K.

Due to the simplicity of their composition, the study of the superconducting properties of elemental substances holds significant importance for understanding the mechanisms of high-temperature superconductivity. This work involves simulated calculations to investigate the phase transition sequence and superconducting properties of Sr under pressure. The stability range of the Sr-IV phase 2/ was redefined, determining that it can extend up to 150 GPa, and the phase transition sequence of Sr under high pressure was studied.

Emerging superconductivity rules in rare-earth and alkaline-earth metal hydrides.

Hydrides of alkaline-earth and rare-earth metals have garnered significant interest in high-temperature superconductor research due to their excellent electron-phonon coupling and high upon pressurization. This study explores the electronic structures and electron-phonon coupling of metal hydrides XH ( = 4,6), where X includes Ca, Mg, Sc, and Y. The involvement of d-orbital electrons alters the Fermi surface, leading to saddle-point nesting and a charge density wave (CDW) phase transition, which opens the superconducting gap.

Structural, elastic, mechanical, electronic, and optical properties of cubic KPbO from first-principle study.

Context: Based on first principles, the structure, elasticity, mechanics, electronics, and optical properties of cubic KPbO were studied. The structural parameters calculated by this method are close to the previous theoretical results. The elastic constant, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and mechanical stability are studied, and it is shown that cubic KPbO is mechanically stable, isotropic, and brittleness.

The structural, mechanical and electronic properties of Ti-Al-based compounds by first-principles calculations.

The first-principles calculations with density functional theory were performed to investigate the effects of transition metal elements (Mo, Cu, Fe, Ni and Nb) on the physical properties of the Ti-Al-based compounds. Our optimized crystal parameters are in good agreement with the previous theoretical and experimental values. The mechanical stability is verified by the independent elastic constants.

The study of spectroscopy and vibrational assignments of high nitrogen material 1,1'-azobis-1,2,3-triazole.

Benefiting from the new strategy of oxidative azo coupling of the N-NH moiety, a series of energetic nitrogen-rich molecules with long catenated nitrogen chains have been successfully synthesized. As one of them, the synthesized 1,1'-azobis-1,2,3-triazole shows excellent thermal stability, great explosive performance, and special photochromic properties, which has caused widespread concern. To further characterize its performance, the structural, electronic, vibrational, mechanical, and thermodynamic properties of 1,1'-azobis-1,2,3-triazole were investigated based on the first-principles density functional theory calculations.

Effects of molecular vacancy and ethylenediamine on structural and electronic properties of CHNO surfaces.

The structural and electronic properties of (100) surface for nitromethane (NM) are studied using density functional theory (DFT) with the generalized gradient approximation and Perdew-Burke-Ernzerhof functional (GGA-PBE). Molecular vacancy and ethylenediamine (CHN) substitution are considered in this work. We find that ethylenediamine substitution significantly decreases the band gap, while molecular vacancy increases the band gap slightly.

Judging the phase transition pressure of the unknown parent phase if the resulting state is known.

In high-pressure phase transition experiments, the crystal structure of the intermediate phase in some phase transitions is difficult to successfully measure due to the limitations of the experimental conditions. The absence of crystal structure data for the intermediate phase also makes it difficult to calculate the pressure point from the intermediate phase to the new phase by the traditional thermodynamic criterion in theoretical simulations. The Conch Criterion is employed by us to successfully verify the phase transition points by observing the reverse shifts of the DOS (electron density of states) curves for the new phase of Cu2S, PbS, PbSe and PbTe, which breaks through the constraints of the traditional criterion and realizes tracing the source of the phase transition in theoretical calculations.

A new criterion for the prediction of solid-state phase transition in TMDs.

The classical thermodynamic criterion for phase transition predicts whether the phase transition will occur according to whether the nth derivative of the state parameter is discontinuous, and the continuity verification of multi-order derivatives increases the difficulty and complexity of judgment for phase transition to a certain extent. Based on the reverse shifts of the DOS curves near the Fermi level, we propose a new criterion for solid-state phase transition named Conch Criterion, which has been verified in the TMD system. The new criterion can observe the occurrence of phase transition from another perspective besides the thermodynamic properties while mutually confirming the thermodynamic criterion.

Transfer of intensity quantum correlation with twin beams.

We demonstrate experimentally a protocol of transferring nonclassical quantum properties using two pairs of quantum-correlated twin beams in the continuous variable regime. The intensity quantum correlation from one twin beam is transferred to two initially independent idler beams with the help of a displacement transformation. It makes two originally independent beams exhibit an intensity quantum correlation of 0.