A running problem in codeml.Please help!!

[pan pan]

Hello anyone

   There is a issue with running codeml，I use 13 datasets, running free-ratio model.When running to the third dataset, the log  file shows “

108 h-m-p  0.0000 0.0000 2654926.2607 +YCYYC 18669.320222  4 0.0000 33608 | 10/157
109 h-m-p  0.0000 0.0000 5454.5229 +CYCYCCC 18658.154322  6 0.0000 33926
fh = -443555085.462882 negative ."

At the same time codeml stops running.I do not kown this meaning. So I need your help.My codeml.ctl file is as follows.

seqfile = pcg.PML
treefile = RAxML_bestTree.out
outfile = rate.out
noisy = 9
verbose = 1
getSE = 0
RateAncestor = 0
fix_blength = 1
seqtype = 1
CodonFreq = 2
cleandata = 0
ndata = 13
clock = 0
icode = 1
Mgene = 0
Small_Diff = .5e-6
model = 1
NSsites = 0
fix_omega = 1
omega = 0.5
fix_alpha = 1
alpha = 0
Malpha = 0
ncatG = 10
fix_kappa = 0
kappa = 2
method = 0

[Ziheng]

you can separate the dataset into a different file, and run the program a few times to see whether it makes a difference.

the free-ratios model (model = 1) tends to have difficult optimisation issues.

how large is the dataset.

ziheng