Dear Prof. Kazume Nishidate, Is not that if we know the system is metallic glass then gamma-point calculation is the only possibility. I mean one can always go ahead with the minimum triclinic symmetry. But as the system in metallic glass then the enthalpy values for calculation considering triclinic symmetry can be higher ( as compared to gamma-point calculation). Kindly let me know your suggestions.
Thanking you, Best regards, Krishnendu ---------------------------------------------------------------------------------------------------------------------------------------------------- Dear Jayraj; > the temperature fluctuations are too high compared to the other > literature. > Because you are using "thousands of atoms" in LAMMPS while you are using only the 128 atoms in QE. > MD simulation of thousands of atoms in LAMMPS ……. > On my metallic system, which has 128 atoms, You must understand the concept > of ensemble average. A good text was introduced by Nicola: > 3) not sure where to start - you need to learn and understand MD - a > good > start is if you google "ercolessi md primer" In addition to his elemental > comments, I want to add some trivial things. > "conv_thr" (i.e. ecutwfc=5 or 10) below a minimum cutoff of > > pseudopotential? So that I can get the next ionic position very Suppose you > have a potential curvature having a shape like a cup and a ball is falling along its curvature from its edge. The ball will perform oscillating behavior continually if there is no energy loss by a friction (energy conservation). In a primitive molecular dynamics calculation (MD), total energy (kinetic+potential) must be preserved in the long time scale (say 10000 time steps) when the system does not have a restriction on its kinetics (like temperature regulation). The "ecutwfc=5" apparently insufficient to evaluate the potential curvature and hence your MD calculation will collapse. It is equivalent to a MD in LAMMPS with random interaction potentials. Use the default cutoff energy and monitor the fluctuation of total energies in the MD runs with changing the dt (time increment value) to find the appropriate (largest) dt with preserving the total energies. And you can also consider a gamma-point only calculation if your system is large enough. 西館数芽 Kazume NISHIDATE Ph.D Department of Systems Innovation Engineering, Graduate School of Science and Engineering, Iwate University 4-3-5 Ueda, Morioka, Iwate, 020-8551 JAPAN
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