[Pw_forum] Surface Passivation in slabs of III-V material using pseudo hydrogen

[Piyush Kumar]

Dear all,

I am trying to calculate the bandstructure of InAs slab using QE-5.1.1.
But, I am getting lots of surface states. I tried hydrogen passivation, but
it did not work. In one paper [1], it has been mentioned that to passivate
the surface dangling bonds in III-V materials, we need to use pseudo
hydrogen atoms having fractional charges. I found this feature in another
DFT tool called ATK (
http://quantumwise.com/documents/tutorials/latest/InAs-2D/index.html/chap.slab.html),
but did not understand how to do the same in Quantum Espresso.

[1] Li, J., & Wang, L. W. (2005). Band-structure-corrected local density
approximation study of semiconductor quantum dots and wires. Physical
Review B, 72(12), 125325.

Here is my input file for bands


 calculation = 'bands',
 prefix = 'inas',
 pseudo_dir = '/home/piyukr/Software/QE/upf_files/',
 outdir = '/home/piyukr/quantum_espresso/inas_slab/six_layer/tmp/'
/

 ibrav=0,
 celldm(1)=8.095332,
 nat=16,
 ntyp=3,
 ecutwfc=60,
 ecutrho=480,
 occupations='smearing'
 smearing='gauss'
 degauss=0.001,
/

 mixing_beta = 0.7,
 conv_thr =  1.0d-10,
/
ATOMIC_SPECIES
 As 74.921600   As.pbe-n-rrkjus_psl.0.2.UPF
 H 1.007940 H.pbe-rrkjus_psl.0.1.UPF
 In 114.818000  In.pbe-dn-rrkjus_psl.0.2.2.UPF
ATOMIC_POSITIONS crystal
 As 0.50 0.00 0.301627
 In 0.50 0.50 0.341301
 As 0.00 0.50 0.380976
 In 0.00 0.00 0.420651
 As 0.50 0.00 0.460325
 In 0.50 0.50 0.50
 As 0.00 0.50 0.539675
 In 0.00 0.00 0.579349
 As 0.50 0.00 0.619024
 In 0.50 0.50 0.658699
 As 0.00 0.50 0.698373
 In 0.00 0.00 0.738048
 H  0.247778 0.00 0.757709
 H -0.247778 0.00 0.757709
 H  0.25 0.00 0.281966
 H  0.747778 0.00 0.281966
CELL_PARAMETERS
1.00 0.00 0.00
0.00 1.00 0.00
0.00 0.00 8.911321
K_POINTS crystal_b
3
0.5 0.0 0.0 30
0.0 0.0 0.0 30
0.5 0.5 0.0 1

I am also attaching my bandstructure.


Thanking you,
Piyush Kumar
M.Tech. Student
Indian Institute of Technology (IIT) Kanpur,
India


bands.pdf
Description: Adobe PDF document
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[Pw_forum] about MPI and OpenMP threads for QE-GPU

[Mutlu COLAKOGULLARI]

Dear All,
I am trying to do some calculations on simple silicon with GPU support as a 
test case before proceeding serious work. 
QE-GPU has been installed by intel cluster suite 13, cuda 5.5 and latest svn 
commits of QE and QE-GPU. 
MANUAL_DFLAGS  = -D__MPICH_SKIP_MPICXX -D__ISO_C_BINDING -D__VERBOSE
DFLAGS =  -D__INTEL -D__FFTW3 -D__MPI -D__PARA -D__SCALAPACK 
-D__ELPA -D__CUDA -D__PHIGEMM -D__OPENMP $(MANUAL_DFLAGS)
I have for 4 nodes. Each one has 24 cores and 2 GPU support so totally 
96 cores + 8 GPU. 
I haven't got any problem for 1 node. I did it. When I passed to bigger 
than 1 node I am getting warnings, for example,
***WARNING: unbalanced configuration (1 MPI per node, 2 GPUs per node)
***WARNING: unbalanced configuration (13 MPI per node, 2 GPUs per node)
So, I am in trouble for sharing the cores between MPI and threads for 
OpenMP. 
Question: How should I share the cores between MPI and OpenMP threads? 
Here is my case:
#SBATCH -N 4
#SBATCH -n 4
#SBATCH --gres=gpu:2
module load centos6.4/lib/cuda/5.5
 export OMP_NUM_THREADS=24
 export MKL_NUM_THREADS=$OMP_NUM_THREADS
 export PHI_DGEMM_SPLIT=0.975
 export PHI_ZGEMM_SPLIT=0.975
mpirun pw-gpu.x -nd 1 < si.in > out.GPU
Sincerely Yours,
 Mutlu.
--Mutlu ÇOLAKOĞULLARITrakya 
Universitesi Fen FakultesiFizik Bolumu22030 Merkez-EDIRNE/TURKEY
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[Pw_forum] nanosheet

[Mahya Zare]

Can anyone help me to make scf calculation input file in quantum espresso
for flat type single atom layer CeO2
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Re: [Pw_forum] Langevin dynamics

[Mahya Zare]

Can anyone help me to make scf calculation input file in quantum espresso
for flat type single atom layer CeO2 nanosheet?

On Mon, Aug 24, 2015 at 6:08 PM, xiaochuan Ge  wrote:

>
> On 20 August 2015 at 00:40, Venkataramana Imandi <
> venkataramana.ima...@gmail.com> wrote:
>
>> Venkataramana
>
>
> Dear ​Venkataramana,
>
> I have some experience using the Langevin code. ​Before we go further to
> understand your problem, I would suggest you to significantly lower the dt
> and try again. Please try dt=0.2 instead of 20. If it still does not work,
> please let me know.
>
> ​Best, ​
>
> ===
> Dr. Xiaochuan Ge (Giovanni)
> Center for Functional Nanomaterials
> Brookhaven national laboratory
> ===
>
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Re: [Pw_forum] Langevin dynamics

[xiaochuan Ge]

On 20 August 2015 at 00:40, Venkataramana Imandi <
venkataramana.ima...@gmail.com> wrote:

> Venkataramana


Dear ​Venkataramana,

I have some experience using the Langevin code. ​Before we go further to
understand your problem, I would suggest you to significantly lower the dt
and try again. Please try dt=0.2 instead of 20. If it still does not work,
please let me know.

​Best, ​

===
Dr. Xiaochuan Ge (Giovanni)
Center for Functional Nanomaterials
Brookhaven national laboratory
===
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