[Pw_forum] occupation problem when system changes from insulator to metal

[W. YU]

Dear all pw users,

In pwscf, if one wants to do a calculation for metal,
one has to add the following lines:

occupations = 'smearing',
degauss = 0.02,
smearing = 'methfessel-paxton'

or something similar. This is not neccessary for
semiconductor or insulator. Now my quesiton is: What
should I do when I am dealing with a system which is
expected to undergo a transformation from insulator to
metal under high pressure, but I don't know when it
will happens. Of course, I will start without the
above lines, but ... then, when should I add them, or
don't add them at all even if I am sure the state
under investigation is metallic now.  

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