[Pw_forum] Lattice Constant Optimization of Aluminum
PRASENJIT GHOSH
prasenjit at jncasr.ac.in
Thu Apr 26 06:21:26 CEST 2007
Dear Paul,
You are getting zero forces because u have set
tprnfor= .false.
As a result the code is not at all calculating forces on the atoms.
For relaxation cal. u should have set it to .true.
Moreover ur unit cell has only one atom. Hence I don't think there is any
point in using the 'relax' option. Rather u can do a simple scf run and
still get the forces. With 'relax' option u can only relax the coordinates
of the atoms, not the unit cell.
With regards,
Prasenjit.
On Thu, April 26, 2007 9:11, Paul M. Grant said:
> To All:
>
> (BTW: PG: My last note on the "default" value of npk should have been
> termed
> "default maximum." Sorry, but we Americans haven't spoken English since
> 1776. Anyway, thanks for pointing me to the right Fortran routine.)
>
> I'm trying to do a very simple homework problem with PWscf.the
> optimization
> of the lattice constant of aluminum.
>
> Even with a wildly wrong first estimate of celldm(1) of 7.2 (the
> experimental value at RT is 7.665 au), I get zero net individual atomic
> forces and thus no optimization. I've gotten "relax" in PWscf to work
> with
> a lot more complex polymer monoclinic unit cell containing eight atoms and
> two different elements. So, I must be doing something really dumb
> (stupid).maybe I should be using vc-relax instead? Anyway, here's the I/O
> (scusi e grazie):
>
> INPUT
>
> &control
>
> title = '$prefix_root$s$i.rx.in'
>
> calculation = 'relax'
>
> restart_mode = 'from_scratch',
>
> prefix = '$prefix_root$s$i',
>
> pseudo_dir = '/home/pmpgrant/espresso-3.2/pseudo/',
>
> outdir = '$home_root',
>
> verbosity = 'minimal',
>
> tprnfor = .false.,
>
> tstress = .true.,
>
> /
>
> &system
>
> ibrav = 2,
>
> celldm(1) = 7.2,
>
> nat = 1,
>
> ntyp = 1,
>
> ecutwfc = 15,
>
> occupations = 'smearing',
>
> smearing = 'methfessel-paxton',
>
> degauss = 0.05,
>
> la2F = .false.,
>
> /
>
> &electrons
>
> diagonalization = 'david',
>
> conv_thr = 1.0d-12,
>
> mixing_beta = 0.7,
>
> /
>
> &ions
>
> ion_dynamics = 'bfgs',
>
> pot_extrapolation = 'second-order',
>
> wfc_extrapolation = 'second-order',
>
> /
>
> ATOMIC_SPECIES
>
> Al 26.98 Al.vbc.UPF
>
> ATOMIC_POSITIONS
>
> Al 0.00 0.00 0.00
>
> K_POINTS {automatic}
>
> 32 32 32 0 0 0
>
> OUTPUT
>
> The total energy is the sum of the following terms:
>
>
>
> one-electron contribution = 3.23304593 Ry
>
> hartree contribution = 0.01297127 Ry
>
> xc contribution = -1.69806267 Ry
>
> ewald contribution = -5.73107767 Ry
>
> smearing contrib. (-TS) = 0.00011533 Ry
>
>
>
> convergence has been achieved
>
>
>
> Forces acting on atoms (Ry/au):
>
>
>
> atom 1 type 1 force = 0.00000000 0.00000000 0.00000000
>
>
>
> Total force = 0.000000 Total SCF correction = 0.000000
>
> SCF correction compared to forces is too large, reduce conv_thr
>
>
>
>
>
> entering subroutine stress ...
>
>
>
> total stress (Ry/bohr**3) (kbar) P=
> 110.51
>
> 0.00075124 0.00000000 0.00000000 110.51 0.00 0.00
>
> 0.00000000 0.00075124 0.00000000 0.00 110.51 0.00
>
> 0.00000000 0.00000000 0.00075124 0.00 0.00 110.51
>
>
>
>
>
> BFGS Geometry Optimization
>
>
>
> bfgs converged in 1 scf cycles and 0 bfgs steps
>
>
>
> End of BFGS Geometry Optimization
>
>
>
> Final energy = -4.1830078084 Ry
>
>
>
> CELL_PARAMETERS (alat)
>
> -0.500000000 0.000000000 0.500000000
>
> 0.000000000 0.500000000 0.500000000
>
> -0.500000000 0.500000000 0.000000000
>
>
>
> ATOMIC_POSITIONS (alat)
>
> Al 0.000000000 0.000000000 0.000000000
>
>
>
>
>
> Paul M. Grant, PhD
>
> Principal, W2AGZ Technologies
>
> Visiting Scholar, Applied Physics, Stanford University
>
> EPRI Science Fellow (Retired)
>
> IBM Research Staff Member Emeritus
>
> <mailto:w2agz at pacbell.net> w2agz at pacbell.net
>
> <http://www.w2agz.com/> http://www.w2agz.com
>
>
>
>
>
>
>
>
PRASENJIT GHOSH,
Ph. D STUDENT,
THEORETICAL SCIENCES UNIT,
JAWAHARLAL NEHRU CENTRE,
JAKKUR P. O.,
BANGALORE - 560064,
INDIA.
PHONE:+91-80-22082835 (OFFICE)
+91 9880519401 (MOBILE)
More information about the Pw_forum
mailing list