Project: QMC-straintronics - Tuning electronic and optical properties of 2D materials via strain

Prace Call: 17th
ID: 2018184443, Leader: Jaroslav Fabian
Affiliation: Universität Regensburg, DE
Research Field: Chemical Sciences and Materials
Collaborators: Ivan Stich Slovak Academy of Sciences SK , Jan Brndiar Slovak Academy of Sciences SK , Kamil Tokar Slovak Academy of Sciences SK , Robert Turansky Slovak Academy of Sciences SK , Tobias Frank Universität Regensburg DE
Resource Awarded: 36 Mil. core hours on MareNostrum

Abstract

The 2D-straintronic project will employ the best available benchmark electronic structure method, the quantum Monte Carlo (QMC), to study the effects of tuning the band gap of free-standing 2-dimensional (2D) materials by applied strain. Based on our expertise in investigating unstrained phosphorene, two distinct single-layer direct-gap semiconductors are proposed for the study of strained systems: phosphorene and MoS2. Numerous experimental studies on 2D MoS2 suggest strainability of up to 10% and gap tunability in the range from 1.8 to 0 eV; large strainability/gap tunability is expected also for phosphorene. The unprecedented tunability opens up a new window on functionalization of 2D straintronic materials, which is important for optical and electronic applications. However, due to the effect of dielectric environments (substrates and capping) the experimentally measured gaps show spreads by about 1 eV as do the gaps calculated by mainstream DFT/GW methods. We propose quantum Monte Carlo (QMC) as the method of choice to provide the least biased values of the band gap of 2D materials strained or in equilibrium. The project outcome will be benchmark values of the band gap under strain. We also argue that QMC in addition to providing band gaps at least an order of magnitude more accurate than the alternative methods, due to the stochastic nature of the algorithm makes an almost perfect use of the largest supercomputer power making QMC an ideal complement to interpret and understand the straintronic experiments.