[Pw_forum] Re : Learning TDDFT calculation in Atomic label (CH4 molecule) using turbo_lanczos.x and turbo_davidson.x

2017-01-31 Thread prem sen 
Dear Dr. Iurii Timrov,
Thanks for the reply.
I was trying in different way to converge scf calculation in case of carbon
dimer without "smearing". First I converge the system using "smearing" then
again I performed the scf calculation by changing the "restart_mode" from
"from_scratch" to "restart". In this condition, the scf calculation for
carbon dimer is converging & also turbo_davidson.x is possible. Do you
think, this is a right approach ??


Also I have observed that if I am using hybrid functional, the system is
converging normally (keeping the restart_mode = from_scratch & without
"smearing").


Can I compute the absorption spectra for a molecule having triplet ground
state using turbo_davidson.x or turbo_lanczos.x ??











Thanks & regards,
Prem Sen
Ph.D. Student,
IIT Bombay,
Mumbai,India.
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Re: [Pw_forum] Learning TDDFT calculation in Atomic label (CH4 molecule) using turbo_lanczos.x and turbo_davidson.x

2017-01-29 Thread prem sen 
Dear Dr. Iurii Timrov,
 Thanks again for your valuable reply.
I knew, how to check the convergence using both the codes but to cross
verify myself, I asked you the question. Now I get the same absorption
spectra for CH4 molecule using both the code (turbo_lanczos.x &
turbo_davidson.x).

I was also trying for Carbon-dimer. But I am facing a basic problem.
Without using, occupations = "smearing", this system is not getting
converged. If I use "smearing", turbo_davidson.x or turbo_lanczs.x is not
possible. I have tried with different kinds of PPs, "mixing_mode" and
"mixing_beta". Is there any solution for this problem ??

For Example I have used ::


  calculation  = "scf",
  restart_mode = "from_scratch"
  prefix   = "C2",
  pseudo_dir   = "../pseudo/",
  outdir   = "./tmp/",
/

  ibrav = 0,
!  celldm(1) = 20,
  nat   = 2,
  ntyp  = 1,
  ecutwfc   = 25,
  ecutrho   = 250,
  nosym = .true.,
!  occupations = "smearing",
!  smearing  = "mv",
!  degauss   = 0.001,
/

  diagonalization='david'
  mixing_mode = 'plain'
  mixing_beta = 0.6,
  conv_thr =  1.0d-8
/
CELL_PARAMETERS angstrom
15.0  0.0  0.0
 0.0 15.0  0.0
 0.0  0.0 15.0
ATOMIC_SPECIES
C  12.01  C.pbe-rrkjus.UPF
ATOMIC_POSITIONS (angstrom)
C1.255833278   0.00000   0.0
C0.0   0.0   0.0
K_POINTS {Gamma}


Thanks & regards,
Prem Sen
Ph.D. Student,
IIT Bombay,
Mumbai,India.
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Re: [Pw_forum] Learning TDDFT calculation in Atomic label (CH4 molecule) using turbo_lanczos.x and turbo_davidson.x

2017-01-24 Thread prem sen 
Dear Dr. Iurii Timrov,
 Thanks for the reply.
"The two codes (Lanczos and Davidson) must give you the same absorption
spectrum (when both are converged)."

How to check the convergence for both the codes ??

I was checking the optical absorption spectra for CH4 molecule (using the
given example for the TDDFPT package) using both the code. They are not
matching with each other.


Also I was trying to do for Carbon-dimer.  In this case also, the spectrum
using both the codes are not matching with each other.  The input files are
given below.

I have checked the ecut & ecutfock convergence and also relaxed the
structure.

*For turbo_davidson.x ::*



*PW.X:*
  calculation  = "scf",
  restart_mode = "from_scratch"
  prefix   = "C2",
  pseudo_dir   = "../pseudo/",
  outdir   = "./tmp/",
/

  ibrav = 0,
  nat   = 2,
  ntyp  = 1,
  ecutwfc   = 75,
  ecutfock  = 75,
  nosym = .true.,
  input_dft = 'PBE0',
  x_gamma_extrapolation = .false.,
  exxdiv_treatment = 'vcut_spherical',
/

  conv_thr= 1.D-10,
  mixing_beta = 0.6,
  adaptive_thr = .true.,
/
CELL_PARAMETERS angstrom
10.0  0.0  0.0
 0.0 10.0  0.0
 0.0  0.0 10.0
ATOMIC_SPECIES
C  12.01  C.pbe-mt_gipaw.UPF
ATOMIC_POSITIONS (angstrom)
C1.248029552   0.0   0.0
C0.0   0.0   0.0
K_POINTS {Gamma}


*Turbo_davidson.x:*_input
prefix="C2",
outdir="./tmp/",
/
_dav
ecutfock  = 75,
num_eign=30,
num_init=60,
num_basis_max = 300,
residue_conv_thr = 1.0E-4,
start = 0.0
finish = 1.0,
step = 0.0005,
broadening = 0.005,
reference = 0.0,
d0psi_rs = .true.,
lshift_d0psi = .true.,
p_nbnd_virt = 20
/


*For turbo_lanczos.x ::*

I used the same file for pw.x as given above.




*Turbo_lanczos.x:*_input
prefix="C2",
outdir="./tmp/",
restart_step=500,
/
_control
itermax=2000,
ipol=4,
ecutfock  = 75,
pseudo_hermitian = .true.,
d0psi_rs = .true.,
/




*Turbo_spectrum.x:*_input
  prefix='C2',
  outdir="./tmp/",
  itermax0 = 410
  itermax  = 1
  epsil=0.01
  start=0.0d0
  end=1.50d0
  increment=0.001d0
  ipol=4
/



Thanks & regards,
Prem Sen
Ph.D. Student,
IIT Bombay
*,*
Mumbai,India
*.*
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[Pw_forum] Learning TDDFT calculation in Atomic label (CH4 molecule) using turbo_lanczos.x and turbo_davidson.x

2017-01-19 Thread prem sen 
Dear All,
I am a new user of QE and interested to calculate the optical
absorption spectra in atomic level using TDDFT code. I have checked the
ecut & ecutfock convergence and also relaxed the structure. I can
understand so far what is going on. But when I am running turbo_lanczos.x
and turbo_davidson.x, I am getting output but how can I check that my
calculation is correct ??
After running turbo_davidson.x, I am getting a file named as "CH4.plot". If
I am plotting it using xmgrace, it is showing the x-axis in Ry scale but
that I want in eV ??



Thanks,
Prem
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