In my case, I have a system of 54 zrcu atoms. i want to melt it at higher temperatures above 2000K and then i will do quenching to get amorphorse metallic alloys state. But shorter time step in cg method give more time consuming. So i choose dt = between 30 to 60 and in order to get equilibrium at high temperatures i took nstep = above 500. For equilibrium i have to run continue till 3 to 5 ps to get randomisation so it took large time to complete. Any suggestions ?
Thank you Jayraj Anadani On Thu, 15 Sep, 2022, 1:28 pm Kazume NISHIDATE, <nisid...@iwate-u.ac.jp> wrote: > Dear, Jayraj Anadani > > > According to the user guide of cp.x we can use a larger time step > > "dt" for electron dynamics = "cg" but for my system of 54 atoms > > (metallic) at 2000 K temperature, it takes a lot of time to take 500 > > steps for 36 core, 72 nodes. > > The temperature 2000 K is very high and the ions must have high > velocities. It means that the ionic positions at the next time step > will largely different from the current ones. The convergence of the > wave functions will need many 'cg' steps accordingly. > > So, you should set short 'dt' to ensure the first convergence of the > wave functions. > > > 1) is there any way to balancing between timestep "dt" and number of > > CP-MD steps "nstep" to achieve fast simulation ?, > > It is worth to try the shorter time intervals (dt) with fixing other > parameters such as the total time steps. > > > 2) In comparison with VASP most of the simulation like NVT, NPT, NVE > > took 3 to 5 ps to equilibrate at a certain temperature so is there > > any strategy to speed up the calculation ? > > Generally, 3 to 5 ps is enough to achieve equilibrium state. But I do > not understand your system and not sure if it is appropriate to your > case. > > > 2022/09/15 16:18、Jayraj Anadani <jayrajanad...@spuvvn.edu>のメール: > > > > Hello QE Community, > > According to the user guide of cp.x we can use a larger time step "dt" > for electron dynamics = "cg" but for my system of 54 atoms (metallic) at > 2000 K temperature, it takes a lot of time to take 500 steps for 36 core, > 72 nodes. > > 西館数芽 > Kazume NISHIDATE Ph.D > > _______________________________________________ > 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 users@lists.quantum-espresso.org > 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 users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
