qvasp: A flexible toolkit for VASP users in materials simulations

We have developed a flexible toolkit, named qvasp (quickly use vienna ab-initio simulation package), to assist users to prepare input files and process output files for Vienna Ab-initio Simulation Package (VASP) during materials simulations. Here, we systematically introduced its design architecture and techniques, as well as how to use qvasp to save time and energy during the materials calculations. This program offers a user-friendly Linux-based command-line interface and aims to help users perform various materials simulations through VASP on high performance computing platform, such as structure optimization, single point energy, work function, electronic structure simulations, mechanical and optical property calculations. In particular, this toolkit provides the basic functions to roll up nanotube from nanosheet and cleave surface from bulk, it also provides an interface for users to customize their own workbags (such as constructing heterojunction structure). All features are designed user-friendly, elegantly and efficiently. We believe this toolkit will be helpful for the users in the field of computational materials science.