An ab initio study of spectroscopic and thermodynamic characteristics of MgH 2 and TiC systems R.M. Arif Khalil a,* , Fayyaz Hussain a,** , Muhammad Imran b , Umbreen Rasheed a , Anwar Manzoor Rana a , G. Murtaza c a Materials Research Simulation Laboratory, Department of Physics, Bahauddin Zakariya University, Multan, 60800, Pakistan b Department of Physics, Govt. College University, Faisalabad, 38000, Pakistan c Centre for Advanced Studies in Physics, Govt. College University, Lahore, 54000, Pakistan article info Article history: Received 3 July 2018 Received in revised form 27 October 2018 Accepted 21 January 2019 Available online xxx Keywords: Lattice dynamics Hydrogen release temperature Harmonic approximation Density functional theory Thermodynamics abstract In this investigation, structural, dynamical and thermodynamic characteristics of mag- nesium hydride (MgH 2 ) and titanium carbide (TiC) are performed through first principle calculations based on the density functional theory (DFT). The lattice dynamics were investigated using the finite displacement supercell approach and thermodynamic calcu- lations were carried out using the harmonic approximation. The modes of vibrations were studied to explore the behavior of individual atoms. The minimum hydrogen release temperature was noted to be Tc ¼ 719 K when only electronic and vibrational free energies of MgH 2 and TiC systems are considered at pressure of 1 bar. However, a remarkable reduction in hydrogen release temperature is noticed in MgH 2 and TiC system i.e. Tc ¼ 321 K (fall of 398 K) by including all the contributions of free energies (i.e. electronic, translational, rotational and vibrational) of hydrogen molecule. © 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction Search for new clean and renewable energy resources has made the vital role of hydrogen in sustainable energy sys- tems [1e3]. Storage of hydrogen in compact volume due to significant gravimetric quantity of H 2 is still a challenging field in the progress of rapidly emergent energy sources. Therefore, the choice of hydrogen storage materials and hydrogen release temperature play key role in the realm of hydrogen storage [4e6]. In this regard, metal hydrides particularly magnesium hydride provides good storage ca- pabilities along with various production, distribution, transportation and consumption issues in the reversible energy applications [7,8]. Moreover, the highest hydrogen storage capacity (of 7.6% by weight), light weight, economics and cyclability have made magnesium hydride the most vital substance in this field/industry [9,10]. Addition of some catalyst has proved to be an applaudable way to enhance the hydrogenation and dehydrogenation * Corresponding author. ** Corresponding author. E-mail addresses: muhammadarif@bzu.edu.pk (R.M. Arif Khalil), fayyazhussain248@yahoo.com (F. Hussain). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (xxxx) xxx https://doi.org/10.1016/j.ijhydene.2019.01.198 0360-3199/© 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article as: Arif Khalil RM et al., An ab initio study of spectroscopic and thermodynamic characteristics of MgH 2 and TiC systems, International Journal of Hydrogen Energy, https://doi.org/10.1016/j.ijhydene.2019.01.198