[ase-users] NEB does not converge

[Nguyen Ngoc Ha]

Dear ASE Users,
I have a problem when doing a CI-NEB job. Here is my input:
 
from ase import *
calc = Siesta('1',basis='DZP',
xc='PBE',
meshcutoff=50*Ry,
pulay=15,
mix=0.15,
charge=0,
kpts=[1, 1, 1])
calc.set_fdf('WriteDM', 'F')
calc.set_fdf('WriteCoorXmol', 'T')
calc.set_fdf('ElectronicTemperature', 0.003 * Ry)
calc.set_fdf('OccupationFunction', 'FD')
calc.set_fdf('PAO.EnergyShift', 0.25 * eV)
calc.set_fdf('PAO.SplitNorm', 0.15)
calc.set_fdf('SpinPolarized', 'yes')
calc.set_fdf('MaxSCFIterations', 20)
calc.set_fdf('SaveMemory', 'T')
initial = read('initial.xyz')
initial.set_cell([
(15, 0, 0),
(0, 15, 0), 
(0, 0, 15)
])
initial.set_pbc((0,0,0))
#initial.center()
final = read('final.xyz')
final.set_cell([
(15, 0, 0),
(0, 15, 0), 
(0, 0, 15)
])
final.set_pbc((0,0,0))
#final.center()
constraint = FixAtoms(indices=(0,1,2,3,4,5,6,7,8,12,13,14,15,16,17))
images = [initial]
for i in range(3):
image = initial.copy()
image.set_calculator(calc)
image.set_constraint(constraint)
images.append(image)
images.append(final)
neb = NEB(images, climb=True, k=0.2)
neb.interpolate()
qn = QuasiNewton(neb, trajectory='neb.traj')
qn.run(fmax=0.05)

 
Many different values of k (0.1, 0.2, ..., 0.7) and number of images (5,7,9,11) were tested but I couldn't get the convergence.
Would you please help me to solve this problem?
Best Regards,

Nguyen, Ngoc Ha
Hanoi National University of Education
Faculty of Chemistry
Department of Physical Chemistry
Tel: Office: 04/8330842
Home: 04/7891674
Mobile: 0989133436


      
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