Thank you Nicola sir for your reply, and sorry for repeating the message. Actually, I am trying to obtain the metallic glass configuration through AIMD using the pw.x code. My system has 128 atoms of Zr and Cu.
- *VASP procedure:* first melted at 3000K using a nose thermostat up to 5 picoseconds, then quenched at a high cooling rate of 10e13 K/s and reached 300K temperature. - *For the Quantum Espresso procedure,* I already used the cp.x code with the nose-hoover thermostat, but due to the metallic nature of Zr and Cu, I couldn't control the electron's adiabaticity. and if I perform the CG method in cp.x code, that will take too much time because of my computational limitations. So I prefer MD simulation using pw.x with "david" diagonalization. As the nose thermostat is not available in pw. x code, so I am using a "rescaling" thermostat for melting and "reduce-T" for quenching. However, the temperature fluctuations are too high compared to the other literature. regards jayraj On Wed, 18 Oct, 2023, 5:41 pm Nicola Marzari via users, < [email protected]> wrote: > > Hi Jayraj, > > you wrote several times, but probably many did not know where to start - > because you are addressing several complex problems without seeming to > have much background in the field. Answers to your 3 points: > > 1) you will not get anything meaningul with the low cutoffs you suggest, > just random stuff. use the minimum cutoffs suggested in my point 2) here > below. > > 2) not sure - pseudopotentials are like people, they can be messed up > deep inside. use the SSSP 1.3 efficiency: > https://www.materialscloud.org/discover/sssp/table/efficiency > > 3) not sure where to start - you need to learn and understand MD - a > good start is if you google "ercolessi md primer" > > nicola > > > > > On 18/10/2023 11:18, Jayraj Anadani wrote: > > Hello, QE community! > > On my metallic system, which has 128 atoms, I am running AIMD > > calculations using the pw.x code. Two pseudopotentials, PAW and USPP, > > were each tested individually. I have the following queries: > > > > 1. For a faster AIMD calculation at a specific temperature, *Can I > > perform the whole simulation with a very low "ecutwfc" and > > "conv_thr" (i.e. ecutwfc=5 or 10) below a minimum cutoff of > > pseudopotential? *So that I can get the next ionic position very > > quickly with a fast scf cycle, then at the last MD step I will > > perform a single point energy (SCF) calculation with high "ecutwfc" > > and "conv_thr" to maintain a good amount of accuracy. > > 2. Compared to PAW pseudopotential, USPP's convergence occurs *much > > more quickly. why*? (when ecutwfc is 25) > > 3. The temperature fluctuation is incredibly small and nearly equal in > > the MD simulation of thousands of atoms in LAMMPS at a specific > > temperature (i.e., 1000K). However, the temperature fluctuation in > > MD with pw.x (AIMD) is significant, so we must set "tolp" which > > stands for tolerance for velocity rescaling. Although the average > > temperature is kept constant, *how closely does this significant > > fluctuation match the LAMMPS MD simulation?* > > > > Thank you > > > > regards > > JAYRAJ ANADANI > > Department of Physics > > SPU Research scholar > > > > _______________________________________________ > > The Quantum ESPRESSO community stands by the Ukrainian > > people and expresses its concerns about the devastating > > effects that the Russian military offensive has on their > > country and on the free and peaceful scientific, cultural, > > and economic cooperation amongst peoples > > _______________________________________________ > > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > > users mailing list [email protected] > > https://lists.quantum-espresso.org/mailman/listinfo/users > > -- > ---------------------------------------------------------------------- > Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL > Director, National Centre for Competence in Research NCCR MARVEL, SNSF > Head, Laboratory for Materials Simulations, Paul Scherrer Institut > Contact info and websites at http://theossrv1.epfl.ch/Main/Contact > > _______________________________________________ > The Quantum ESPRESSO community stands by the Ukrainian > people and expresses its concerns about the devastating > effects that the Russian military offensive has on their > country and on the free and peaceful scientific, cultural, > and economic cooperation amongst peoples > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
