Although the energy has converged, the RMS isn’t getting any smaller, and seems to be ‘stuck’ at a constant value.
How can I improve the RMS?
What parameter do I change to get it to just accept the current RMS and move onto the next geometry iteration?
While I cannot post the structure in it’s entirety, let me describe the system as completely as I can:
It’s a dimer system consisting of two non-bonded monomer units. Each monomer unit is a (garden variety) bi-aryl that has a protonated amine at one end, and a de-protonated acid at the other end (classic push/pull system); the overall system is neutral. Also note that a single monomer unit does converge (even with just DIIS under version 1.5)
The starting geometry for psi4 came from a semi-empirical calculation via XTB (GFN2-xTB). I have tried two different XTB starting geometries and saw the same RMS issue with both.
I am using Psi4 1.5 (and ma attempting to upgrade, but am having issue)
Here’s the input file parameters (I’ve tried several basis sets at this point and have also used b3lyp-d3bj) →
set scf_type df
set basis 6-31G(d_p)
set reference rks
mol.update_geometry()
mol.symmetrize(1e-3)
e, wfn = optimize('b3lyp', return_wfn=True)
oeprop(wfn, "MULLIKEN_CHARGES")
mol.print_out()
print_variables()
Here’s the last steps of the given iteration →
==> Iterations <==
Total Energy Delta E RMS |[F,P]|
@DF-RKS iter 35: -1565.58429333171784 -3.05383e-05 1.18306e-03 DIIS
@DF-RKS iter 36: -1565.58428661289395 6.71882e-06 1.18307e-03 DIIS
@DF-RKS iter 37: -1565.58427872381435 7.88908e-06 1.18308e-03 DIIS
@DF-RKS iter 38: -1565.58428963786287 -1.09140e-05 1.18307e-03 DIIS
@DF-RKS iter 39: -1565.58428269595538 6.94191e-06 1.18308e-03 DIIS
@DF-RKS iter 40: -1565.58428432227720 -1.62632e-06 1.18308e-03 DIIS
@DF-RKS iter 41: -1565.58428601946093 -1.69718e-06 1.18307e-03 DIIS
@DF-RKS iter 42: -1565.58428358918013 2.43028e-06 1.18308e-03 DIIS
@DF-RKS iter 43: -1565.58428516316621 -1.57399e-06 1.18308e-03 DIIS
@DF-RKS iter 44: -1565.58428477465213 3.88514e-07 1.18308e-03 DIIS
@DF-RKS iter 45: -1565.58428440906641 3.65586e-07 1.18308e-03 DIIS
@DF-RKS iter 46: -1565.58428495098451 -5.41918e-07 1.18308e-03 DIIS
@DF-RKS iter 47: -1565.58428459385368 3.57131e-07 1.18308e-03 DIIS
@DF-RKS iter 48: -1565.58428468662214 -9.27685e-08 1.18308e-03 DIIS
@DF-RKS iter 49: -1565.58428476502786 -7.84057e-08 1.18308e-03 DIIS
@DF-RKS iter 50: -1565.58428464436361 1.20664e-07 1.18308e-03 DIIS
@DF-RKS iter 51: -1565.58428472528931 -8.09257e-08 1.18308e-03 DIIS
@DF-RKS iter 52: -1565.58428470326794 2.20214e-08 1.18308e-03 DIIS
@DF-RKS iter 53: -1565.58428468647639 1.67915e-08 1.18308e-03 DIIS
@DF-RKS iter 54: -1565.58428471334310 -2.68667e-08 1.18308e-03 DIIS
@DF-RKS iter 55: -1565.58428469500745 1.83356e-08 1.18308e-03 DIIS
@DF-RKS iter 56: -1565.58428470022113 -5.21368e-09 1.18308e-03 DIIS
@DF-RKS iter 57: -1565.58428470380500 -3.58386e-09 1.18308e-03 DIIS
@DF-RKS iter 58: -1565.58428469783030 5.97470e-09 1.18308e-03 DIIS
@DF-RKS iter 59: -1565.58428470197896 -4.14866e-09 1.18308e-03 DIIS
@DF-RKS iter 60: -1565.58428470074773 1.23123e-09 1.18308e-03 DIIS
@DF-RKS iter 61: -1565.58428469998626 7.61474e-10 1.18308e-03 DIIS
@DF-RKS iter 62: -1565.58428470131480 -1.32854e-09 1.18308e-03 DIIS
@DF-RKS iter 63: -1565.58428470037711 9.37689e-10 1.18308e-03 DIIS
@DF-RKS iter 64: -1565.58428470066701 -2.89901e-10 1.18308e-03 DIIS
@DF-RKS iter 65: -1565.58428470082890 -1.61890e-10 1.18308e-03 DIIS
@DF-RKS iter 66: -1565.58428470053059 2.98314e-10 1.18308e-03 DIIS
@DF-RKS iter 67: -1565.58428470074432 -2.13731e-10 1.18308e-03 DIIS
@DF-RKS iter 68: -1565.58428470067770 6.66205e-11 1.18308e-03 DIIS
@DF-RKS iter 69: -1565.58428470064223 3.54703e-11 1.18308e-03 DIIS
@DF-RKS iter 70: -1565.58428470070658 -6.43468e-11 1.18308e-03 DIIS
@DF-RKS iter 71: -1565.58428470065996 4.66116e-11 1.18308e-03 DIIS
@DF-RKS iter 72: -1565.58428470067474 -1.47793e-11 1.18308e-03 DIIS
@DF-RKS iter 73: -1565.58428470068384 -9.09495e-12 1.18308e-03 DIIS
@DF-RKS iter 74: -1565.58428470067020 1.36424e-11 1.18308e-03 DIIS
@DF-RKS iter 75: -1565.58428470067929 -9.09495e-12 1.18308e-03 DIIS
@DF-RKS iter 76: -1565.58428470067497 4.32010e-12 1.18308e-03 DIIS
@DF-RKS iter 77: -1565.58428470067543 -4.54747e-13 1.18308e-03 DIIS
@DF-RKS iter 78: -1565.58428470067815 -2.72848e-12 1.18308e-03 DIIS
@DF-RKS iter 79: -1565.58428470067679 1.36424e-12 1.18308e-03 DIIS
@DF-RKS iter 80: -1565.58428470067565 1.13687e-12 1.18308e-03 DIIS
@DF-RKS iter 81: -1565.58428470067543 2.27374e-13 1.18308e-03 DIIS
@DF-RKS iter 82: -1565.58428470067543 0.00000e+00 1.18308e-03 DIIS
@DF-RKS iter 83: -1565.58428470067588 -4.54747e-13 1.18308e-03 DIIS
@DF-RKS iter 84: -1565.58428470067724 -1.36424e-12 1.18308e-03 DIIS
@DF-RKS iter 85: -1565.58428470067588 1.36424e-12 1.18308e-03 DIIS
@DF-RKS iter 86: -1565.58428470067497 9.09495e-13 1.18308e-03 DIIS
@DF-RKS iter 87: -1565.58428470067747 -2.50111e-12 1.18308e-03 DIIS
@DF-RKS iter 88: -1565.58428470067452 2.95586e-12 1.18308e-03 DIIS
@DF-RKS iter 89: -1565.58428470067406 4.54747e-13 1.18308e-03 DIIS
@DF-RKS iter 90: -1565.58428470067588 -1.81899e-12 1.18308e-03 DIIS
@DF-RKS iter 91: -1565.58428470067543 4.54747e-13 1.18308e-03 DIIS
@DF-RKS iter 92: -1565.58428470067429 1.13687e-12 1.18308e-03 DIIS
@DF-RKS iter 93: -1565.58428470067679 -2.50111e-12 1.18308e-03 DIIS
@DF-RKS iter 94: -1565.58428470067543 1.36424e-12 1.18308e-03 DIIS
Other things I’ve tried →
- damping_percentage → 20-40%
- diis_max_vecs → 50-100 (info I found here)
- changing initial guess → huckel
- making the grid finer →
set dft_spherical_points 434
set dft_radial_points 85
set dft_pruning_scheme robust