[Pw_forum] Structural optimization

[Sunetra Das]

Hello Everybody,

I am new to QE and trying to learn structural optimization.
Are the two terms 'structural relaxation' and 'structural optimization'
synonymous ? If yes, then is it meaningful to carry out any structural
optimization on an unit cell only or is it more meaningful to optimize the
supercell structure? My system has a 4x4 supercell structure of 32 atoms.
Also can anybody please guide me through the correct sequence of steps to
optimize a structure? Should I carry out a 'relax' calculation and follow
it by a 'vc-relax' and then finally a 'scf' calculation? Or can I do a
'vc-relax' in the very first go without any 'relax' calculation?
Is it mandatory to mention the 'dt' parameter for a 'vc-relax' run?

Kindly help.

Regards,

Sunetra Das
Assistant Professor,
Maharaja Manindra Chandra College,
Kolkata, India.
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