On 2019-04-23 13:52, Aliya Qureshi wrote:
Hello QE Users,
I am trying to generate 3IFC file for Silicon and is facing some
issues with it. The 3ifc generated don’t decay after a point and
because of which I am getting incorrect values for calculation
following it.
Using, shengBTE I generate my displaced super-cell files, and then use
these as input files by Quantum Espresso for calculating the forces
arising from atomic displacements. Then, I generate the force
constants using those files. But, the force constants which I am
getting tends not to decay after a point.
Attached is a plot for the 3IFC generated. The horizontal axes is the
sum of the three distances between the atoms defining a triplet and
the vertical axis is the Frobenius norm of the 3x3x3 matrix of
third-order force constants for that triplet.
Can you please guide me with this, I am a new user to QE, any guidance
is appreciated.
Thank You.
Best,
Aliya Qureshi
NanoEnergy and Thermophysics Lab
Electrical and Computer Engineering Dept.
University of Massachusetts Amherst
##########################################################################################
Below are the files in order:
1. The input file of unit cell
2. A template input file for supercell calculations
3. DISP.si_supercelltemplete.in (snippet)
4. DISP.si_supercelltemplete.out (snippet)
5. Snip from 3IFC file
*******************Si.scf_thirdorder.in*******************************
&CONTROL
calculation='scf', prefix='Si', restart_mode='from_scratch',
tstress = .true., tprnfor = .true.,
/
&SYSTEM
ibrav=2, celldm(1)=10.263, nat=2, ntyp=1, ecutwfc=38.0
ecutrho=151.0
/
&ELECTRONS
conv_thr=1.0d-9,
/
ATOMIC_SPECIES
Si 28.0855 Si.pbe-n-kjpaw_psl.0.1.UPF
ATOMIC_POSITIONS crystal
Si 0.00 0.00 0.00
Si 0.25 0.25 0.25
K_POINTS gamma
***********************************Si_supercelltemplete.in***************************
&CONTROL
calculation='scf', prefix='Si', tstress = .true.' tprnfor = .true.,
outdir = '/project/si_supercelltemplete##NUMBER##
pseudo_dir = '/home/aq26a/qe/q-e-qe-6.2.1/pseudo/'
/
&SYSTEM
ibrav=0, nat=##NATOMS##, ntyp=1, ecutwfc=38.0 ecutrho=151.0
/
&ELECTRONS
conv_thr = 1.0d-9
/
ATOMIC_SPECIES
Si 28.0855 Si.pbe-n-kjpaw_psl.0.1.UPF
##COORDINATES##
K_POINTS gamma
##CELL##
*******************************DISP.si_supercelltemplete.in***************************
&CONTROL
calculation='scf',
prefix='Si',
tstress = .true.' tprnfor = .true., outdir =
'/project/si_supercelltemplete1' pseudo_dir =
'/home/aq26a/qe/q-e-qe-6.2.1/pseudo/'
/
&SYSTEM
ibrav=0, nat=128, ntyp=1, ecutwfc=38.0 ecutrho=151.0 /
&ELECTRONS
conv_thr = 1.0d-9
/
ATOMIC_SPECIES
Si 28.0855 Si.pbe-n-kjpaw_psl.0.1.UPF
ATOMIC_POSITIONS crystal
Si -0.00092064996812095 0 0.00092064996812095
Si 0.0625 0.0625 0.0625
Si 0.25 0 0
Si 0.3125 0.0625 0.0625
Si 0.5 0 0
Si 0.5625 0.0625 0.0625
Si 0.75 0 0
Si 0.8125 0.0625 0.0625
Si 0 0.25 0
Si 0.0625 0.3125 0.0625
.
.
.
.
Si 0.75 0.75 0.75
Si 0.8125 0.8125 0.8125
K_POINTS gamma
CELL_PARAMETERS angstrom
-10.8618914313439 0 10.8618914313439
0 10.8618914313439 10.8618914313439
-10.8618914313439 10.8618914313439 0
****************************DISP.si_supercelltemplete.out******************************
.
.
.
5.0482 5.0482 5.0482 5.0482 5.0482 5.4882 5.4882 5.4882
5.4882 5.4882 5.4882 5.4882 5.4882 5.4882 5.4882
5.4882
5.4882 5.4882 5.4882 5.4882 5.4882 6.2518 6.2518
6.2518
highest occupied level (ev): 6.2518
! total energy = -5980.18082331 Ry
Harris-Foulkes estimate = -5980.18082330 Ry
estimated scf accuracy < 1.6E-10 Ry
total all-electron energy = -74248.451930 Ry
The total energy is the sum of the following terms:
one-electron contribution = 367.11806762 Ry
hartree contribution = 71.80268742 Ry
xc contribution = -785.10766678 Ry
ewald contribution = -1074.94517644 Ry
one-center paw contrib. = -4559.04873514 Ry
convergence has been achieved in 13 iterations
Forces acting on atoms (cartesian axes, Ry/au):
atom 1 type 1 force = 0.00000000 0.00000000
-0.00000000
atom 2 type 1 force = 0.00000010 -0.00000010
-0.00000010
atom 3 type 1 force = 0.00000002 -0.00000014
-0.00000002
.
.
.
***********************3IFC
file********************************************
Snippet from 3ifc file: where the structure description is as:
• A blank line
• A 1-based sequential index
• A line with the Cartesian coordinates of the second unit cell in
Å
• A line with the Cartesian coordinates of the third unit cell in
Å
• A line with the 1-based indices of the three atoms involved, each
from 1 to natoms
• 27 lines, each of which starts with a tern of integers specifying
three Cartesian axes and is completed by a force constant in
eV/Å<sup>3</sup>. The last element of the tern changes first
1
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
1 1 1
1 1 1 0.0000000000e+00
1 1 2 0.0000000000e+00
1 1 3 0.0000000000e+00
1 2 1 0.0000000000e+00
1 2 2 0.0000000000e+00
1 2 3 -3.1541466075e+01
1 3 1 0.0000000000e+00
1 3 2 -3.1541466075e+01
1 3 3 0.0000000000e+00
2 1 1 0.0000000000e+00
2 1 2 0.0000000000e+00
2 1 3 -3.1541466075e+01
2 2 1 0.0000000000e+00
2 2 2 0.0000000000e+00
2 2 3 0.0000000000e+00
2 3 1 -3.1541466075e+01
2 3 2 0.0000000000e+00
2 3 3 0.0000000000e+00
3 1 1 0.0000000000e+00
3 1 2 -3.1541466075e+01
3 1 3 0.0000000000e+00
3 2 1 -3.1541466075e+01
3 2 2 0.0000000000e+00
3 2 3 0.0000000000e+00
3 3 1 0.0000000000e+00
3 3 2 0.0000000000e+00
3 3 3 0.0000000000e+00
2
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
1 1 2
1 1 1 2.9619109574e+00
1 1 2 -5.9122449335e+00
1 1 3 -5.9122449335e+00
1 2 1 -6.1143664229e+00
1 2 2 6.1143664229e+00
1 2 3 7.9842098089e+00
1 3 1 -6.1143664229e+00
1 3 2 7.9842098089e+00
1 3 3 6.1143664229e+00
2 1 1 -6.1143664229e+00
2 1 2 6.1143664229e+00
2 1 3 7.9842098089e+00
2 2 1 5.9122449335e+00
2 2 2 -2.9619109574e+00
2 2 3 -5.9122449335e+00
2 3 1 7.9842098089e+00
2 3 2 -6.1143664229e+00
2 3 3 -6.1143664229e+00
3 1 1 -6.1143664229e+00
3 1 2 7.9842098089e+00
3 1 3 6.1143664229e+00
3 2 1 7.9842098089e+00
3 2 2 -6.1143664229e+00
3 2 3 -6.1143664229e+00
3 3 1 5.9122449335e+00
3 3 2 -5.9122449335e+00
3 3 3 -2.9619109574e+00
3
0.0000000000e+00 0.0000000000e+00 0.0000000000e+00
-2.7154728578e+00 0.0000000000e+00 2.7154728578e+00
1 1 1
1 1 1 1.5105231662e-01
1 1 2 -5.4158751476e-02
1 1 3 -1.9328736602e-01
1 2 1 -5.1574972130e-02
1 2 2 -1.1306403226e-01
1 2 3 -6.3804775915e-02
1 3 1 -2.2537028746e-01
1 3 2 4.5126069497e-03
1 3 3 2.2537028746e-01
2 1 1 -5.1574972130e-02
2 1 2 -1.1306403226e-01
2 1 3 -6.3804775915e-02
2 2 1 -1.2593092626e-01
2 2 2 1.5722908765e-02
2 2 3 1.2593092626e-01
2 3 1 -6.3804775915e-02
2 3 2 1.1306403226e-01
2 3 3 -5.1574972130e-02
3 1 1 -2.2537028746e-01
3 1 2 4.5126069497e-03
3 1 3 2.2537028746e-01
3 2 1 -6.3804775915e-02
3 2 2 1.1306403226e-01
3 2 3 -5.1574972130e-02
3 3 1 1.9328736602e-01
3 3 2 -5.4158751476e-02
3 3 3 -1.5105231662e-01
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