Computational Study of the inorganic and hybrid functional materials for (spin) electronics and chemical transformations

Dnr:

SNIC 2017/3-62

Type:

SNAC Small

Principal Investigator:

Weiwei Sun

Affiliation:

Uppsala universitet

Start Date:

2017-06-30

End Date:

2018-07-01

Primary Classification:

10304: Den kondenserade materiens fysik

Webpage:

- Kebnekaise at HPC2N: 5 x 1000 core-h/month
- Abisko at HPC2N: 5 x 1000 core-h/month

1. The combination of spintronics and molecular electronics is an emerging research field due to the possibility of manipulating spin and charge degrees of freedom at the atomic scale. The possibility of controlled spin manipulation makes these magnets attractive for device applications including spin-dependent electronics and molecular switches.
Crown ether molecules, as the name suggests, are composed of rings of polar C-O-C chains (with H bonds as required to eliminate dangling bonds). A single crown ether molecule is referred to as N-crown-M, where N is the total number of C and O atoms and M is the number of ether chains. A monolayer of crown ethers can be viewed as a sheet of graphene into which vacancies and O substitution have been introduced, and prior work suggests that such a structure would exhibit an enhanced ability to incorporate atoms or molecules within the cavity compared to the free-standing molecule and would therefore prove attractive as a host for molecular spintronics devices. The investigation of the crystal, electronic, and magnetic structure of crown ethermolecules and monolayers with TM atoms incorporated into the cavity will be the initial focus of our investigation. Later work could focus on manipulation of the coupling between the dressed crown ethers via empty cavities or interaction with, e.g., a Fe or Ni thin film substrate, with additional quantum control coming from strain and variation of N and M (leading to varying TM-O bond lengths and coordination numbers). The dependence of electron correlation, charge transfer, and hybridization on these parameters should lead to interesting and tunable physical phenomena that would be of considerable technological and fundamental interest. The the electronic properties can be obtained using the Dynamical mean-filed approximation (DMFT)
Implemented in RSPt code.
2. Few-layer black phosphorus (BP) is a novel two-dimensional (2D) semiconductor with a number of remarkable properties such as strong anisotropy and pronounced thickness dependence of its electronic characteristics, as well as high current on-off ratios and high carrier mobilities. Consequently, BP is a promising candidate for diverse electronic and optical applications.
It is well-known that one-particle DFT often fails to produce accurate band gaps, while more consistent results with respect to the electronic properties can be obtained using the QSGW approximation. However, GW calculations come with their own difficulties due to the dependence on the starting point, self-consistent Green function, and/or and the model used to obtain W. In this study, we will perform a systematic study on multilayers of BP by quasi-particle self-consistent GW approach and also the structural deformation by the weak VDW forces. Combing these two factors, we can pave the way of how to produce an accurate band gap of BP, with technical and scientific results that will give insights to many other monolayers.