[Pw_forum] Force calculation time in relaxation under electric field
myoussef at mit.edu
Mon Sep 21 04:21:23 CEST 2015
I performed ionic relaxation for 3x3x3 unit cells of a semiconducting oxide under electric field (lelfield =.true.) using ultrasoft PP and 1x1x3 MP K-point grid where 3 is in the direction of the electric field. These are GGA+U calculations. I noticed in the time report that force calculations time is becoming even more than the electrons time as shown below:
init_run : 8.32s CPU 8.91s WALL ( 1 calls)
electrons : 42723.25s CPU 44995.21s WALL ( 5 calls)
update_pot : 2.62s CPU 3.19s WALL ( 4 calls)
forces : 66735.95s CPU 66943.64s WALL ( 5 calls)
This is first time in which I find PWscf use more time in force calculations than in electrons. For the same system and without electric field , forces time would be about 0.2 of electrons time. Is this a normal behavior and is there a recommended possibility to reduce force calculation time?
I attempted using Norm Conserving PP's but unfortunately I could not get the code pass the 1 ionic step because of the S matrix not being positive definite.
I appreciate your thoughts on this.
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