Dear users and developers,
I'm very new to using MRCC and already think it's quite cool. I came across an issue and couldn't find anything about it in the manual so far.
I am currently trying to compute CCSD(T) of (closed shell) [Fe(H
2O)
6]
2+ and am encountering convergence issues in both the SCF and CCSD iterations. I was able to solve the SCF issues. Are there ways to speed up or help CCSD convergence along aside from increasing the number of iterations? It is increasingly slow and I am unsure why.
Thanks in advance!
Input:
Code:
# CCSD(T)
calc=CCSD(T)
mem=100000MB
mult=1
charge=2
scfmaxit=50
scfext=15
scfdamp=0.7
scflshift=0.25
scfiguess=ao
#qscf=AugHessL
basis=atomtype
Fe:cc-pwCVTZ
O:cc-pCVDZ
H:cc-pVDZ
core=corr
unit=angs
geom=xyz
19
Fe 0.000000000 0.000000000 0.000000000
O 0.000000000 0.000000000 1.989595000
H -0.789066000 0.002150000 2.555337000
H 0.789066000 -0.002150000 2.555337000
O -0.036065000 1.989327000 0.000000000
H -0.007113000 2.554548000 0.788946000
H -0.007113000 2.554548000 -0.788946000
O -1.989619000 -0.009611000 0.000000000
H -2.547156000 0.785416000 0.000000000
H -2.563405000 -0.792705000 0.000000000
O 0.000000000 0.000000000 -1.989595000
H 0.789066000 -0.002150000 -2.555337000
H -0.789066000 0.002150000 -2.555337000
O 0.036065000 -1.989327000 0.000000000
H 0.007113000 -2.554548000 -0.788946000
H 0.007113000 -2.554548000 0.788946000
O 1.989619000 0.009611000 0.000000000
H 2.547156000 -0.785416000 0.000000000
H 2.563405000 0.792705000 0.000000000
Output snippet:
Code:
Starting CCSD iterations...
Residual norm Energy
Iteration 1 4.274088814384 -1719.550464222440
Iteration 2 6.484609056622 -1719.842522232327
Iteration 3 2.193209171674 -1720.033668644362
Iteration 4 1.980510710749 -1720.209594806344
Iteration 5 2.002652643973 -1720.345925538991
Iteration 6 1.239898116240 -1720.413527453012
Iteration 7 0.726006191715 -1720.461212885563
Iteration 8 0.565702744661 -1720.507344600944
Iteration 9 0.484284282073 -1720.543777687296
Iteration 10 0.371546782703 -1720.565270711646
Iteration 11 0.287244841891 -1720.578718665980
Iteration 12 0.245685775346 -1720.588653602694
Iteration 13 0.196006045394 -1720.595537426124
Iteration 14 0.147666442792 -1720.599459234976
Iteration 15 0.116515619156 -1720.601980166463
Iteration 16 0.101014030733 -1720.603678087391
Iteration 17 0.083979696661 -1720.604643284147
Iteration 18 0.066517805798 -1720.605170933782
Iteration 19 0.052176645444 -1720.605607293077
Iteration 20 0.044106502967 -1720.606030554397
Iteration 21 0.037077658969 -1720.606359059045
Iteration 22 0.030265135499 -1720.606527785491
Iteration 23 0.024271261951 -1720.606576605529
Iteration 24 0.020425249901 -1720.606588491923
Iteration 25 0.017028052329 -1720.606612637738
Iteration 26 0.013649564313 -1720.606645937079
Iteration 27 0.011383525498 -1720.606666868290
Iteration 28 0.009686951664 -1720.606677923058
Iteration 29 0.008139587728 -1720.606693398128
Iteration 30 0.006869743029 -1720.606716792576
Iteration 31 0.005807696774 -1720.606740604099
Iteration 32 0.004866826676 -1720.606754073281
Iteration 33 0.004171591320 -1720.606755069804
Iteration 34 0.003652780662 -1720.606748737499
Iteration 35 0.003078183214 -1720.606742609954
Iteration 36 0.002677137847 -1720.606744787171
Iteration 37 0.002440727451 -1720.606756613783
Iteration 38 0.002151469817 -1720.606768501056
Iteration 39 0.001986561378 -1720.606773601665
Iteration 40 0.001918707880 -1720.606774806203
Iteration 41 0.001929114539 -1720.606777488375
Iteration 42 0.001784663811 -1720.606782974503
Iteration 43 0.001730907738 -1720.606791820029
