Skip to content

Unphysical effective mass tensor for valence band in monolayer 2H-VS2 #196

Description

@SinghZimmi

Dear Wannier_tools developers and users,

I am calculating the hole effective mass tensor for the valence band maximum (7th wannierized bands) of monolayer 2H-VS2 at the Γ point, but getting unphysical results(~25m₀). Additionally, the electron effective masses for the 7th spin-down wannierized bands are provided in the spindown folder. Note that the wannierization was performed separately for the spin-up and spin-down bands. A gap exists between the 7th spin-up wannierized band (VBM) and the 7th spin-down wannierized band (CBM).
I have plotted the Wannier-interpolated bands (using WannierTools BulkBand_calc), and the bands folder is included in the shared link. A 4th-order polynomial fit directly on the DFT bands around the VBM gives a reasonable hole effective mass of ~3.20 m₀, but WannierTools results are very different.

Results:
k-step = 0.00005 Å⁻¹:
-25.24581391 0.02471383 -64.83941230
0.02471383 -25.22779510 32.01864958
-64.83941230 32.01864958 ***************

k-step = 0.01 Å⁻¹
-308.84540770 130.84252471 ********
130.84252471 -85.57102830 ********
The masses are extremely large with huge off-diagonal elements and missing components.

System:
Monolayer 2H-VS2 (non-SOC, ferromagnetic)
Wannier90 HR file from Quantum ESPRESSO+ wannier90
NumOccupied = 7
NK1=801, NK2=801, NK3=1

I have attached the necessary files here: https://drive.google.com/drive/folders/1ZJzrAPL933dLvAe2v3SGQfG3F_ZjlTjq?usp=sharing
(includes vs2.win, wt.in, bands folder, and other relevant files)

Any suggestions on how to improve the effective mass calculation would be greatly appreciated.
Thank you very much for your help!

--
Best Regards
Zimmi Singh
Ph.D Research Scholar
Department of Metallurgical and Materials Engineering,
Indian Institute of Technology Kharagpur, West Bengal, India

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions