[QE-users] Extra states in conduction band and PDOS/Total DOS mismatch in strained hBN unit cell

[Ms. Chandrika K.]

Hello everyone,
I am performing DFT calculations on a pristine and uniaxially strained hexagonal boron nitride (hBN) unit cell using Quantum ESPRESSO with the following computational parameters:

  *   Pseudopotentials: B.pbe-n-rrkjus_psl.1.0.0.UPF and N.pbe-n-rrkjus_psl.1.0.0.UPF (USPP, PBE, scalar relativistic)
  *   ecutwfc: 60 Ry | ecutrho: 480 Ry
  *
K-mesh: 12×12×1 (SCF), 36×36×1 (NSCF)
  *   Broadening: ngauss = 0, degauss = 0.004 Ry, DeltaE = 0.004 eV
  *
DOS tool: projwfc.x only (both total DOS and PDOS from same run)
  *
Basis: Only s and p orbitals present for both B and N

  *
In the pristine unit cell DOS (Figure 1), the total DOS and the sum of B and N projected DOS match upto certain point in the conduction band.

  *
However, in the strained unit cell (Figure 2), additional states at the edge of conduction band are visible  and also the total DOS is not accounted  by either the B or N projected DOS individually or collectively.
Any insights on the origin of the extra conduction band states and the enhanced PDOS mismatch in the strained system would be greatly appreciated.

Chandrika Yadav K


Research Scholar

NanoElectronics Laboratory

Amrita Viswa Vidyapeetham

Bangalore


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