[CP2K-user] [CP2K:16965] Re: Ar Basis sets

[Matthew Graneri]

Hi Marcella

Thank you so much, I can't believe I missed the UZH Ar basis set! To be 
honest, I didn't consider it because I thought that UZH was some 
theoretical method I'd never heard of (like HFX or ADMM), and I only just 
found out it stood for University of Zurich...

Unfortunately, there's no HFX basis set for argon (even on the git 
repository), so I can't use that for my system. Would I be right in 
assuming that, if I use BASIS_ADMM-UZH basis sets, I should also use 
POTENTIAL_UZH and the BASIS_MOLOPT_UZH? Originally, I was going to use the 
DZVP-GTH basis sets because (I believe) they are smaller. I also don't know 
whether the fact that the UZH sets were optimised against the PBE0 will 
cause issues with me using B3LYP as my functional. What do you think?

1) In that case, why would someone equilibrate their system with a MASSIVE 
thermostat first, and then again with a GLOBAL thermostat? This is what is 
done in the IR spec tutorial...
2) I thought that might be the case. Thank you!
3) Of course, that would make life too easy ;)

Thank you so much for your help! I have no experience with any type of bulk 
calculation, so your advice is very much appreciated

Regards,

Matthew
On Friday, May 13, 2022 at 1:37:18 AM UTC+8 Marcella Iannuzzi wrote:

> Dear Matthew
>
> There are Ar ADMM basis sets in BASIS_ADMM_UZH in cp2k/data (at least 
> present git repository)
> The ADMM basis set can be tested against full HFX calculations.
>
> 1) Using MASSIVE there is one  thermostat attached to each degree of 
> freedom, with GLOBAL only one thermostat controls all degrees of freedom
> 2) Larger cutoff are needed to collocate on the real space grid functions 
> with larger exponents. In this respect, yes there is a basis set dependency
> 3) No rule to thumb, it depends what the simulation goals are
>
> Regards
> Marcella
>
>
> On Wednesday, May 11, 2022 at 9:15:36 AM UTC+2 mhvg... at gmail.com wrote:
>
>> Hi there,
>>
>> I was wondering if I could get some advice/help on running an AIMD 
>> calculation to run? I've *no* experience with AIMD, MD, or any plane 
>> wave calculations (my only experience is with ab initio methods in ORCA and 
>> Gaussian), and no one else in my department has any experience with AIMD 
>> calculations, either... I've finally gotten to the stage where I can start 
>> an AIMD calculation (it's taken weeks to get to this stage!), but I have 
>> come across a persistent issue which I do not have the expertise to solve.
>>
>> Essentially, I want to simulate my molecular system in a solid argon 
>> matrix, and calculate IR spectra to compare with experiment. So far, I've 
>> optimised my cutoff/rel_cutoff values, gotten my input files sorted, gotten 
>> CP2K installed installed on our local HPC, and tested that it works for a 
>> few of the test systems provided for the IR/RAMAN and HFX tutorials.
>>
>> Based on results from a recent study, I want to use B3LYP with a double 
>> zeta basis set, which I am very well aware will take a long time to 
>> complete... According to the CP2K website (and my own testing), it looks 
>> like using either the ADMM or RI approximations might speed up this 
>> calculation to a rate which will be acceptable for our HPC. The problem is 
>> that I cannot find any *matching* primary, potential and auxiliary basis 
>> sets for argon. In fact, I cannot find any auxiliary basis sets for argon 
>> at all.
>>
>> Is this because argon doesn't require an aux basis set for RI or ADMM? 
>> Does anyone know of any basis set families which I could use for my 
>> calculations? They'd need to be of at least double zeta quality, and 
>> include basis sets for H, C, N, S and Ar.
>>
>> Also, three unrelated questions (but things which I've been 
>> confused/unsure about when trying to learn all this stuff):
>>
>>    1. what's the difference between the 'global' and 'massive' 
>>    thermostats? The academic (yes, there's only one) at my university who has 
>>    experience with MD had never seen those terms before, so I'm not sure how 
>>    they differ.
>>    2. Are the cutoff/rel_cutoff values basis set dependent? As in, if I 
>>    swap the basis sets I ran my testing on based on advice I get here, would I 
>>    need to rerun my testing for the new basis set, or could I use the values I 
>>    determined using the original basis sets?
>>    3. Are there any 'rules of thumb' as to how big a cell should be used 
>>    for a system like mine? Essentially, I've embedded my molecule in a crystal 
>>    of argon. I'm *not* trying to extrapolate this to a larger crystal 
>>    structure (I think that means it's 'non periodic'?)
>>
>> I'd really appreciate any help I can get with this; I'm very much out of 
>> my depth here...
>>
>> Thanks in advance!
>>
>> Matthew~
>>
>

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/1806b475-c6e1-4706-ad1f-96cda9d019c7n%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20220512/c8a2d91f/attachment-0001.htm>