Greeting, QE users and experts,
I am a little bit confused about force information printed by pw.x:
------START-------
Forces acting on atoms (cartesian axes, Ry/au):
atom 1 type 1 force = -0.00001085 0.00000000 0.00000000
atom 2 type 2 force = 0.00001085 0.00000000 0.00000000
The non-local contrib. to forces
atom 1 type 1 force = -1.19247240 0.00000000 0.00000000
atom 2 type 2 force = 2.35869968 0.00000000 0.00000000
The ionic contribution to forces
atom 1 type 1 force = 10.24429006 -0.00000000 0.00000000
atom 2 type 2 force = -10.24429006 0.00000000 -0.00000000
The local contribution to forces
atom 1 type 1 force = -9.05412227 0.00000000 0.00000000
atom 2 type 2 force = 7.89944406 0.00000000 0.00000000
The core correction contribution to forces
atom 1 type 1 force = 0.00187326 0.00000000 0.00000000
atom 2 type 2 force = -0.01425971 -0.00000000 -0.00000000
The Hubbard contrib. to forces
atom 1 type 1 force = 0.00000000 0.00000000 0.00000000
atom 2 type 2 force = 0.00000000 0.00000000 0.00000000
The SCF correction term to forces
atom 1 type 1 force = 0.00000019 -0.00000000 0.00000000
atom 2 type 2 force = 0.00000184 -0.00000000 -0.00000000
DFT-D3 dispersion contribution to forces:
atom 1 type 1 force = 0.00000264 0.00000000 0.00000000
atom 2 type 2 force = -0.00000264 -0.00000000 -0.00000000
Total force = 0.000015 Total SCF correction = 0.000002
DFT-D3 dispersion Force = 0.000004
-------END--------
(I just take optimization of CO molecule as example.) What make me confused
are,
1. What do two lines below "Forces acting on atoms..." mean? I tried to add
all "contribution" terms (from non-local to dispersion) of one atom together
but found not to equal to 0.00001085.
2. I find that "Total SCF correction" roughly equals to "1.9E-7 + 1.84E-6",
and "DFT-D3 dispersion Force" roughly equals to "|2.64E-6|+|-2.64E-6|".
However, I don't know how to obtain "Total force = 1.5E-5", I tried to sum over
all terms of each atom above it, took their absolute values and add together,
but result was 8.35E-4, not 0.000015 (1.5E-5).
Any answers will be appreciated, thanks in advance!
Best regards!
Yike Huang, PhD candidate.
Dalian Institute of Chemical Physics, CAS, China._______________________________________________
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