quantum-espresso

History

paulatto adf74ca151 Example updated to use standard pseudo from quantum-espresso.org instead of one from theos git-svn-id: http://qeforge.qe-forge.org/svn/q-e/trunk/espresso@13958 c92efa57-630b-4861-b058-cf58834340f0		2017-10-26 07:06:05 +00:00
..
reference	Example updated to use standard pseudo from quantum-espresso.org instead of one from theos	2017-10-26 07:06:05 +00:00
README	New code to compute total energy and phonons in 2D materials by enforcing 2D periodic boundary conditions. Inter-layer Coulomb interaction is truncated. Vacuum space need to be larger than the layer size. Also check phonon example17 and input documentation.	2017-10-25 10:40:59 +00:00
run_example	Example updated to use standard pseudo from quantum-espresso.org instead of one from theos	2017-10-26 07:06:05 +00:00

README

This example illustrates how to use the phonon code to calculate
the dispersions along some the a path of the BZ for two-dimensional materials.
The Gamma-K-M-Gamma path of monolayer Boron Nitride is used as an example.  
The calculation proceeds as follows 

1) make a self-consistent calculation for BN, setting assume_isolated='2D' 
in the SYSTEM namelist to activate the 2D Coulomb cutoff. 
   (input=bn.scf.in, output=bn.scf.out) 

2) make the phonon calculation for a grid of 881 q-points. The 2D Coulomb 
cutoff is automatically activated for a phonon run done on top of a 2D scf run 
(no need to specify any additional flag in the phonon input).

3) interpolate the phonon dispersion using q2r and matdyn. This time, and especially for polar 2D material, one should set :
loto_2d=.true. 
in input so that LO-TO splitting is treated in the correct two-dimensional framework.