Hi,
The phase error due to the beam tilt is proportional to Cs.
See Eq. 4 of https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056894/.
This means that if your Cs is very small (say 0.01), probably you
do not have to refine the beam tilt. It also means that fitting
becomes more difficult, because the beam tilt does not produce
much phase errors.
That being said, the program should not give 'nan'.
I CC-ed this mail to Jasenko, who wrote relion_ctf_refine.
Best regards,
Takanori Nakane
> Hi Maria,
> Was this run on data from Krios2? If so, that is the scope with the Cs
> corrector so the Cs is on the order of a few microns instead of 2.7 mm.
We
> have had strange results when trying to do beam tilt correction with
data
> on this microscope. Does the algorithm rely on having a relative large
(or
> "normal") Cs coefficient?
> Bill
> Sent from my iPhone
> On Aug 28, 2018, at 7:53 AM, Maria Elizabeth Falzone
> <[log in to unmask]<mailto:[log in to unmask]>> wrote:
> Hello CCPEM!
> I have a question about Relion3. I am using it for the first time and
when
> I run the CtfRefine job incluing the option for beam tilt estimation the
> job says "estimating the beamtilt" but the output file reads "nan"
instead
> of a measurement and there is not error anywhere in the output. Has
anyone
> else experience this or have any idea why? Any information would be
> greatly appreciated!
> Thanks!
> -Maria
> ________________________________
> To unsubscribe from the CCPEM list, click the following link:
> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCPEM&A=1
> ########################################################################
> To unsubscribe from the CCPEM list, click the following link:
> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCPEM&A=1
########################################################################
To unsubscribe from the CCPEM list, click the following link:
https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCPEM&A=1
|