Hi all,
I have a question regarding the phonon density-of-states of MgO calculated using library potentials. Following example13, I ran the following code:
############################################################
opti prop conp
cell
4.212000 4.212000 4.212000 90.000000 90.000000 90.000000
fractional
Mg core 0.000000 0.000000 0.000000
Mg shel 0.000000 0.000000 0.000000
O core 0.500000 0.500000 0.500000
O shel 0.500000 0.500000 0.500000
space
225
library …/…/Libraries/bush.lib
dump bush-opt.gin
############################################################
I then extracted the optimized lattice parameters and executed this:
############################################################
phon nofreq
cell
4.20604560 4.20604560 4.20604560 90.00000000 90.00000000 90.00000000
fractional 1
Mg core 0.000000000 0.000000000 0.000000000 1.5800000 1.0000 0.000000
O core 0.500000000 0.500000000 0.500000000 0.5130000 1.0000 0.000000
Mg shel 0.000000000 0.000000000 0.000000000 0.4200000 1.0000 0.000000
O shel 0.500000000 0.500000000 0.500000000 -2.5129999 1.0000 0.000000
space
225
totalenergy -163.9814387900 eV
species 4
Mg core 1.580000
Mg shel 0.420000
O core 0.513000
O shel -2.513000
buck
O shel Mg shel 2457.24300 0.261000 0.000000 0.00 10.00
buck
O shel O shel 25.4100000 0.693700 32.32000 0.00 12.00
spring
Mg 349.95000
spring
O 20.530000
shrink 30
broaden_dos 0.2
box density size 1
output phonon bush-opt
############################################################
Repeating this procedure for several of the libraries listed here, I end up with the Figure attached. The black line is the PDOS calculated in this paper. A similar shape for the PDOS has been reported here.
My question is - have I made a mistake in my input files? Or are the deviations of the various PDOS from the reference just due to differences in the potential parameters?
Thank you very much for your time,
Connor
