[Pw_forum] Langevin dynamics
Venkataramana Imandi
venkataramana.imandi at gmail.com
Thu Aug 20 06:40:35 CEST 2015
Dear Paolo Giannozzi sir,
Thank you sir for your kind reply and sorry for delaying reply. I felt same
thing while reading previous threads in pw_forum archives. According to
suggestions given by Ari Paavo Seitsonen sir, I made all corrections and
tried my level best. All trials lead to collapse of structure during
Langevin dynamics.
Best,
Venkataramana
PhD student
IIT Bombay
Langevin dynamics was implemented many years ago in QE, but I have never
heard of anybody using it, nor seen any evidence that it works (or that it
doesn't).
Paolo
On Mon, Aug 10, 2015 at 1:10 PM, Venkataramana Imandi
<venkataramana.imandi at gmail.com
<http://pwscf.org/mailman/listinfo/pw_forum>> wrote:
Dear Sir/ Madam,
I am using quantum espresso (version:5.1.2) for doing Langevin dynamics on
Ethene molecules were kept top and bottom of silver oxide surface (total
atoms: 37) running on Red Hat machine with serial and parallel process. In
the output file, the coordinates of some of the atoms getting starred(***).
In order to understand more about results, I tried with simple systems
containing 2 Si atoms, the results shows that Langevin dynamics is working
fine but the distance between two Si atoms goes on increasing (at the end
of 100 md steps, the distance is 560 Angstroms). Moreover, herein Langevin
dynamics is over-damped and the parameter of gamma (friction coefficient)
is not mentioned anywhere in the input file description of pw.x related
manual. Hence, I request you kindly suggest me how to perform Langevin
calculations on my original system. Input file and starred(**) coordinates
of my original system (output file) were attached.
&control
calculation='md',
prefix='ag_eth',
dt=20.D0,
nstep=50,
etot_conv_thr=1.0D-6,
forc_conv_thr=1.0D-5,
pseudo_dir = '/home/venkat/ORR1/PPS1'
/
&system
ibrav=0,
nat=37,
ntyp=4,
ecutwfc = 30.0,
nosym=.true.,
occupations='smearing',
smearing='m-p',
degauss=0.03,
tot_charge=1.0
/
&electrons
electron_maxstep=2000,
diagonalization='david',
mixing_beta = 0.3,
conv_thr = 1.0D-6,
scf_must_converge=.false.
/
&ions
pot_extrapolation = 'second_order',
wfc_extrapolation = 'second_order',
ion_dynamics='langevin',
tempw=300.D0,
nraise=1
/
ATOMIC_SPECIES
C 12.0107 C.pbe-rrkjus.UPF
H 1.00794 H.pbe-rrkjus.UPF
O 15.9994 O.pbe-rrkjus.UPF
Ag 107.8682 Ag.pbe-d-rrkjus.UPF
CELL_PARAMETERS {angstrom}
7.8980000000 0.0000000000 0.0000000000
0.0000000000 7.8980000000 0.0000000000
0.0000000000 0.0000000000 9.7479000000
ATOMIC_POSITIONS {angstrom}
C 3.674759 2.942993 -3.493103
H 4.121990 3.816735 -4.007690
H 4.121990 2.069251 -4.007690
C 2.211227 2.942993 -3.493103
H 1.763996 3.816735 -4.007690
H 1.763996 2.069251 -4.007690
O 0.000000 0.000000 -2.719012
Ag 4.448147 4.449893 -1.919012
Ag 4.448147 1.436093 -1.919012
Ag 1.437838 4.449893 -1.919012
Ag 1.437838 1.436093 -1.919012
Ag 2.942993 2.942993 0.000000
Ag 2.942993 0.000000 0.000000
Ag 0.000000 2.942993 0.000000
Ag 0.000000 0.000000 0.000000
Ag 1.437838 1.436093 1.919012
Ag 1.437838 4.449893 1.919012
Ag 4.448147 1.436093 1.919012
Ag 4.448147 4.449893 1.919012
O 0.000000 0.000000 2.719012
C 3.674759 2.942993 3.493103
H 4.121990 3.816735 4.007690
H 4.121990 2.069251 4.007690
C 2.211227 2.942993 3.493103
H 1.763996 3.816735 4.007690
H 1.763996 2.069251 4.007690
O 0.000000 5.885983 -2.719012
Ag 2.942993 5.885983 0.000000
Ag 0.000000 5.885983 0.000000
O 0.000000 5.885983 2.719012
O 5.885983 0.000000 -2.719012
Ag 5.885983 2.942993 0.000000
Ag 5.885983 0.000000 0.000000
O 5.885983 0.000000 2.719012
O 5.885983 5.885983 -2.719012
Ag 5.885983 5.885983 0.000000
O 5.885983 5.885983 2.719012
K_POINTS {gamma}
A BIT of OUTPUT FILE
ATOMIC_POSITIONS (angstrom)
C 23.936881089 5.854758432 2.384283563
H 5.319738992 3.101932011 -2.806230409
H 5.032723666 3.366896985 -3.263624443
C -19.193958442 -0.839672619 -8.633281572
H 2.840673809 3.320817821 -3.598829264
H 2.259010092 3.506469010 -4.024573435
O 3.200827481 3.891444136 -5.674056522
Ag -2.799093034 8.698187934 0.392246441
Ag 6.216802688 0.615454519 -1.827886947
Ag -1.094861601 5.714331653 -3.826763750
Ag -0.821908140 -7.523290040 -8.937996255
Ag 7.394141127 8.391763262 7.199208896
Ag 66.2293865871065.326804153 192.584344197
Ag 4515.057117298 369.600932228 188.645687521
Ag 395.079974228 976.555500510 23.641381229
Ag -0.868373165 1.254442767 -0.725095564
Ag 0.598543920 4.290748028 1.130598433
Ag 3.451303546 0.003835176 -2.147641351
Ag 4.967046204 4.664900169 1.274377193
O 4.154896086 3.538399188 4.404896973
C 399.041692489-175.281493613-563.071390643
H 3.281002088 3.892508380 4.191590229
H 5.590682748 1.083007852 4.528641700
C -206.161786136-122.423501782 -55.021382542
H 0.246549207 5.329189077 3.491183253
H 1.659499381 1.418695757 3.087580955
O -19.384256566 28.168644116 11.242605036
Ag -75.320660159**************-197.570811974
Ag 561.119359654-921.736664610 96.273929826
O 0.652654857 4.794099697 2.674333108
O 0.725736992 1.497121799 -3.145265492
Ag ************** -53.851744674 435.559732159
Ag -59.3881630261875.893021868 -68.801534006
O 4.092070388 0.327775217 7.087480811
O 1.475113672 4.942700103 -3.552674785
Ag -847.347981606************** -58.746720826
O 5.344579864 2.986191369 5.581658260
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