First-principles calculations to investigate structural, electronic, elastic and optical properties of radium based cubic fluoro-perovskite materials oleh Muhammad Khuram Shahzad, Shoukat Hussain, Muhammad Umair Farooq, Rashid Ali Laghari, Muhammad Hamza Bilal, Sajjad Ahmad Khan, Muhammad Bilal Tahir, Adnan Khalil, Jalil Ur Rehman, Muhammad Mahmood Ali