[QE-users] scf calculation of an amorphorse structure from md simulation coordinates

[jayraj anadani]

> Dear QE community,
>
> I have one particular molecular system of 10-20 atoms which I am getting
> from a simulation of a large atom (around 10000 atoms) at a 300K
> temperature from a molecular dynamic simulation (LAMMPS). and I also did
> optimization of MD structure. now if i want to do DFT study to know the
> bonding characteristic (i.e. DOS/PDOS) of atoms, at 300K configuration.what
> is the best way to study dft.
>
> I already did the AIMD/CPMD calculation using *cp.x* code but since my
> material is amorphous metallic and CPMD is too delicate for metals and
> couldn't control the kinetic energy of an electron (*ekin)*.
> so,
> 1. Can I do direct SCF calculation(without relax) by giving a condition of
> *forc_conv_thr* and *tot_conv_thr* with creating a vacuum(for a
> non-periodic system) of around 15 Angstrom to converge properly. *OR*
> 2. I should do the RELAX calculation with vacuum and then go to the *scf*
> calculation to find the total energy and then *nscf*.
>
> ***questions:
> 1. what if I relax a system and position is changed a bit(which is
> obvious) to minimize the total energy but that energy is at zero kelvin dft
> calculation and I want to study the system at 300K. So how can small parts
> of a structure reflect large MD simulation structural properties?
>
> Thank you
>
> Yours Sincerely,
>
>
> Jayraj Anadani
>
> Research Scholar
> Department of Physics, Sardar Patel University
>
> Gujarat, India-388120
>
>
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