graphite in CP2K
Michele Ceriotti
michele.... at gmail.com
Wed May 28 14:20:44 UTC 2014
Dear CP2K community,
I have been trying for a few days to set up calculations of graphite
as an exercise for a student but I am getting the weirdest results. I am
sure in the it will end up being a silly mistake in the input, but I can't
get to see it so perhaps someone can help.
Despite using a fairly large FD smearing, the SCF cycle has a hard time
converging, and when the maximum number of steps is reached
50 Broy./Diag. 0.50E+00 1.2 0.00014351 -819.2909959720
-2.28E-09
*** SCF run NOT converged ***
and the calculation carries on with what it has got, diagnostics are really
strange.
For a start, eigenvalues show two weird very low-energy states
MO EIGENVALUES AND MO OCCUPATION NUMBERS
# MO index MO eigenvalue [a.u.] MO occupation
1 -21.523076 2.000000
2 -21.517160 2.000000
3 -1.383548 2.000000
4 -0.510418 2.000000
forces on the atoms are insane
ATOMIC FORCES in [a.u.]
# Atom Kind Element X Y Z
1 1 C 4.68736611 4.63921800 -222.86999309
2 1 C -1.57720920 -4.48651652 124.33822840
3 1 C -5.01734639 3.10518104 176.16292919
and so is the stress tensor
STRESS TENSOR [GPa]
X Y Z
X -8233.84728056 8.05482610 0.90481573
Y 8.05482610 -9552.76932222 -0.49445437
Z 0.90481573 -0.49445437 -2526.59040628
I was thinking of an error in the structure or the cell parameters, but I
checked it many times and everything seems in order. The same structure,
with same functional and similar parameters in SIESTA converges like a
stone, and gives no problem whatsoever.
Can you spot something obvious that I am missing? I'd really like to use
CP2K for this exercise, but I can't seem to figure out what is going wrong.
Many thanks,
Michele
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