Multiwfn forum

patrickmelix

Member

Registered: 2021-06-16

Posts: 3

Input Problem for PDOS Fragment Definition

Dear Tian Lu,

many thanks for your great Software, which helps me with a lot of tasks.

I have a question regarding the input limitations when defining PDOS fragments:
It seems to me that there is an unmentioned limit on the number of atoms I can add to a fragment at once. If I add a list of approximately 90 atoms at once using the "a 1, 2, 3,...." notation, I get a different number of basis functions added to the fragment than if I add each atom individulally, i.e. "a 1 \n a 2 \n a 3 \n...". I tried checking the source for the relevant part, but could not find it myself.
It took me quite a while to figure this out, as there is no error printed and the only way to catch it is to add the individual PDOS contributions or compare the total number of basis functions manually.

If this is indeed the case, perhaps you might consider putting a warning in the manual or include a safety-check in the input parser.

Please excuse me if I missed an already existing warning or if this was already discussed on the forum, I tried to search thoroughly...

Thanks again for this great software!
Best,
Patrick

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,854

Website

Re: Input Problem for PDOS Fragment Definition

Dear Patrick,

Thank you for your feedback, but I am unable to reproduce the problem you mentioned. For example, I take examples\butadiene.fch as an example, the fragments defined by inputting "a 1,2,3,4,5,6" and "a 1 \n a 2 \n a 3 \n a 4 \n a 5 \n a 6" are exactly the same, see below screenshots, and the resulting PDOS maps are also completely identical.

So, I don't know how to reproduce your observation... (note that I am using latest version of Multiwfn on Multiwfn website).

Best regards,

Tian

patrickmelix

Member

Registered: 2021-06-16

Posts: 3

Re: Input Problem for PDOS Fragment Definition

Dear Tian,

thanks for your quick reply and sorry for the delay...

Yes, I can also reproduce the expected behavior for small systems that you mention. Your test also works fine for me.

In my problematic case, the number of atoms in one line is approx. 90. For such a long list, the results of the two input variants differ. I am also using the latest version. So if you try with a large system and enter many atoms in one line, I expect that you can see the same problem. I was not able to check, but I expect it to be due to some Fortran variable limitation (perhaps the string that is read is limited in size?!).

Thanks for your help!
Best regards,
Patrick

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,854

Website

Re: Input Problem for PDOS Fragment Definition

Please do not input e.g. "a 1 \n a 2 \n a 3 \n", it is much better to simply input "a 1-3". Indeed there is a limit of the string used for loading inputted information, if you select the atomic indices using range input, such as 2,6-12,30,50-80, this limitation will never cause a problem.

patrickmelix

Member

Registered: 2021-06-16

Posts: 3

Re: Input Problem for PDOS Fragment Definition

Ok, thanks for the clarification. Do you know how long the line can be before it breaks? My system is not well ordered, so just want to make sure that the "1-3" notation is not still too long.
Is there another downside beyond speed to using "a 1 \n a 2 \n a 3 \n"? Will the results somehow be affected?

Thanks again for all your help, I greatly appreciate you taking the time to answer all my questions.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,854

Website

Re: Input Problem for PDOS Fragment Definition

Ok, thanks for the clarification. Do you know how long the line can be before it breaks? My system is not well ordered, so just want to make sure that the "1-3" notation is not still too long.
Is there another downside beyond speed to using "a 1 \n a 2 \n a 3 \n"? Will the results somehow be affected?

Thanks again for all your help, I greatly appreciate you taking the time to answer all my questions.

I just updated Multiwfn on Multiwfn website, currently each line at most accepts 2000 characters. In the old version each line can at most accepts only 200 characters.