Dears
I am doing QM/MM calculations and trying to optimize a Gaussian input file of about 35000 atoms. QM region contains 60 atoms. But after a long time, I got an error that Max no. of micro-iterations restarts exceeded. Can anyone help me out?
Format of input file;
%chk=/home/SKD/work/gaussian/calculations/g23.chk
%mem=32GB
%nproc=16
#n oniom(hf/6-31g:UFF) opt=ReadFreeze scf=(xqc,maxcycle=1000)
Ms. Ivanova
The following is the end format of output file:
Largest displacement in micro-iterations: 0.00D+00
Fragment: 1 Trans scale: 1.0000 Rot scale: 0.0438
NRF= 1 NRA= 67 NVA=1808 HaveQM=F NVQ= 0
Convergence limit is 0.300E-04 MaxStp=106584 StMxLn= 1.00D-04 StpMin= 1.00D-06.
Convergence criteria 0.00004500 0.00003000 0.00018000 0.00012000
Step NS ND Rises OKQ Scale Max. Force RMS Force Max. Disp. RMS Disp. Energy Flag
Large rigid frag rotational dispacement found.
Stepping infringing coordinate back!
1 0 0 F T 1.00D+00*********** 9.56403368*********** 3.61008792 800.5021897 XXXX
Largest displacement in micro-iterations: 0.00D+00
Max number of microiteration restarts exceeded.
Error termination via Lnk1e in /home/SKD/work/gaussian/l103.exe at Tue May 9 04:00:08 2017.
Job cpu time: 0 days 18 hours 31 minutes 35.8 seconds.
File lengths (MBytes): RWF= 1438 Int= 0 D2E= 0 Chk= 1019 Scr= 2
"g25.log" 281448L, 15244807C 281448,2 Bot
If gaussian failed to even converge the geometry optimization first step, I would say that the starting structure is probably very far from the optimum or has some structural problems.
Dear Trzaskowski
I understand the fact that structure is probably very far from the optima but can you suggest me how to deal with this error (Max number of microiteration restarts exceeded.)
Hi, Shashi
Did you solve the problem related to "Max number of micro iterations restarts exceeded"?@shashi kumar
Arghya Pratim Ghosh Yes, I did. Actually, I was getting this problem because my system geometry was very far from the optimum. So what I did that I took the last system coordinates and submitted again along with opt= quadmacro in the route section of Gaussian input file. Sometimes, 'maxcycle=N', (increasing number of cycles) solve the problem.
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