The relative stability, physical and chemical properties of MoSe₂ and MoTe₂: First principal investigation

Lathifa Banu S¹, Vasu Veerapandy ¹ and Ponniah Vajeeston*² 

¹Department of Computational Physics, School of Physics, Madurai Kamaraj University, Madurai 625021, Palkalai Nagar, Tamil Nadu, India

²Department of Chemistry and Center for Materials Science and Nanotechnology, University of Oslo, Oslo 0371, Norway

Email: ponniahv@kjemi.uio.no, vasu.physics@mkuniversity.org ,lathifabanu@gmail.com 

Abstract: In recent articles, the family of Transition Metal Dichalcogenides (TMDCs) materials has received a lot of interest for numerous applications. The most significant feature of TMDCs material is its layer nature, which may be easily modified for applications such as electrochemical, photocatalytic, and optoelectronic systems. Even with laking of the structural stability, TMDCs materials are still remarkable. In this paper, first-principles calculations based on density functional theory (DFT)are used to conduct in-depth studies for various polymorphs of MoSe₂ and MoTe₂. The inner structure of both MoSe₂ and MoTe₂  is tightly connected as a two-dimensional layer or sandwiches that are loosely related to one another by relatively weak van der Waals-type forces. A single layer of MoSe₂ and MoTe₂ will have a trigonal prismatic phase with a hexagonal structure or an octahedral prismatic phase with a trigonal polymorph. In this study, we investigated the relative stability of alternative hexagonal and trigonal structures for both MoSe₂ and MoTe₂ polymorphs (see the Figure 1). According to our simulation, the numerous polymorphs of the MoSe₂ and MoTe₂polymorphs of hexagonal and trigonal structures appear to have the same minimum energy, but with a wide range of volume. In comparison to MoTe2 polymorphs the energy value of MoSe2 polymorphs is low. The electronic characteristics of the phases involved were computed using the hybrid functional of Heyd, Scuseria, and Erhzerhof (HSE06). Single crystal elastic constant and phonon investigations were also used to explore the mechanical and dynamical stability of all of these phases. Finally, we discovered that four polymorphs of MoSe₂ and MoTe₂ are mechanically and dynamically stable. since these polymorphs can essentially synthesize. The stable polymorphs of MoSe₂ polymorphs and MoTe₂  polymorphs were anticipated.

Keywords_: Density functional theory, Relative stability, Phonon.

 Reference:

1. D. Kong, H. Wang, J.J. Cha, M. Pasta, K.J. Koski, J. Yao, Y. Cui, Synthesis of MoS2 and MoSe2 films with vertically aligned layers, Nano Lett. 13 (2013) 1341–1347, http://dx.doi.org/10.1021/nl400258t. 
2. W. Kohn and L. J. Sham, Phys. Rev., 1965, 140, A1133–A1138

1. First-principles calculations of structural, electronic, and optical properties MoX2 (X = S, Se) metal dichalcogenides and their Nano-layers Ahmad Mashmool, Parviz Saeidi, Shahram Yalameha, Zahra Nourbakhsh