Pressure effect on structural stability and optical absorption of triclinic NbS 3 from DFT and many-body perturbation ca
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THE EUROPEAN PHYSICAL JOURNAL B
Regular Article
Pressure effect on structural stability and optical absorption of triclinic NbS3 from DFT and many-body perturbation calculations Bonaventure Dusabe 1,2,a , Guy Mo¨ıse Dongho-Nguimdo 3,4 , and Daniel P. Joubert 5 1
2 3
4 5
Institute of Mathematics and Physical Sciences (IMSP), University of Abomey-Calavi, 01 BP 613 Porto-Novo, Benin Faculty of Engineering, University of Burundi, Bujumbura, Burundi College of Science, Engineering and Technology, University of South Africa, PO Box 392, UNISA 0003 Pretoria, South Africa College of Technology, University of Buea, PO Box 63, Buea, Cameroon The National Institute for Theoretical Physics, School of Physics and Mandelstam Institute for Theoretical Physics, University of the Witwatersrand, Johannesburg, Wits 2050, South Africa Received 1 February 2020 / Received in final form 6 May 2020 Published online 1 July 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. In this paper, we investigated the structural stability, mechanical, vibrational, electronic, and optical properties; and the exciton binding energy of the quasi 1D transition metal trichalcogenide NbS3 under pressure. The structural properties are in good agreement with previous computational and experimental studies. Calculated elastic constants satisfy the Born stability criteria and suggest that NbS3 is mechanically stable against distortion under pressure up to 4.84 GPa. Vibrational properties via phonon calculations showed that NbS3 is dynamically stable when submitted to small atomic displacements. The results predict the maximum optical absorption coefficient of the bulk NbS3 at 5.13 × 105 cm−1 and it occurs in the visible range spectrum at 3.09 eV. From G0 W0 and BSE calculations, we found that the size of the optical bandgap reduces from 1.01 to 0.48 eV as the pressure increases from 0 to 4 GPa. Our calculations also predicted the existence of bound excitons with binding energy ranges from 130 to 160 meV.
1 Introduction Transition metal trichalcogenides (TMTC) have the general formula MX3 where M is a transition metal belonging to IV and V groups (Ti, Zr, Hf, Nb, Ta, W), and X a chalcogenide atom (S, Se, Te). This family of materials has attracted the attention of many workers over years because of their unusual properties such as metal-insulator Peierls and charge density waves (CDW) [1–3]. They are also predicted to find many applications in the semiconductor industry [4], and are promising materials for third generation of solar cells [5,6] as well as rechargeable batteries [7]. Most of the bulk TMTC are layered materials and composed of two dimensional sheets held together by a weak van der Waals forces. It has been shown that the electronic properties of some of them, such as ZrS3 and HfS3 , can be tuned by applying strain [8]. It is reported that five different phases of NbS3 have been synthesized up to date: NbS3 -I [9], NbS3 -II [10], NbS3 -III [11], NbS3 -IV a
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