The  paper of  the  month,  chosen  by  the Editor-in-Chief,  is  "Designing a Novel Trigonal Silicon Material: First-Principles Calculations"  by Q. Fan, Y. Li, R. Yang, X. Yu, and S. Yun;

DOI: 10.12693/APhysPolA.145.273

Silicon is one of the most studied materials due to its applications in the electronic industry. Silicon crystals can come in many allotropic types, two allotropes exist at room temperature: amorphous and crystalline with the diamond structure. Many other allotropes have been synthesized. Using first-principles density functional theory (DFT)  the  paper  predicts a new silicon allotrope called Tri-Si18. The atomic structure of Tri-Si18 belongs to the space group P3221 (trigonal crystal system), the unit cell contains 18 Si atoms and consists of five- and six-membered rings. A comprehensive study of structural, energetic, mechanical, electronic and thermal properties of this structure is presented in the paper and the system is shown to be stable. Mechanical, electrical and thermal properties of such crystals are found. The calculated electronic properties show that the system is an indirect band gap semiconductor with the energy gap of 1.77 eV.

All these properties of the novel silicon allotrope are very attractive. I am looking forward to the time when this form of silicon will be synthesized.

The Editor-in-Chief