[CP2K-user] [CP2K:19245] When to use LSD option?

[Moon Yue]

Dear Mr. Watkins

Thank you for your comments.
So do you mean that smearing of electrons can't be used when UKS is set ?

Yue

在2023年7月31日星期一 UTC+9 22:04:02<Matt Watkins> 写道：

> Hello,
> the LSD (or UKS etc) allows the spin up and spin down orbitals to relax 
> independently due to the different exchange interactions. There are other 
> methods (ROKS for instance, though less often used) that allow open shell 
> calculations without this extra freedom. 
> So you need to specify the charge, the multiplicity and the method (LSD).  
> This doesn't apply to metallic systems where you have smearing of 
> electrons.
> Matt
>
> On Saturday, 29 July 2023 at 19:37:28 UTC+1 Niharendu Choudhury wrote:
>
>> I am still confused. CHARGE and MULTIPLICITY KEYWORDS are not enough to 
>> describe the unpaired electrons in the systems?
>> Do I need to use SPIN_POLARIZED or UKS in addition to the above keywords? 
>> What is the meaning of LSD then?
>>
>> @Prof. Hutter or any other developers please clarify.
>>
>> Cheers
>> Niharendu Choudhury
>>
>> On Wed, Jul 26, 2023 at 7:21 PM Martin Konôpka <konop... at gmail.com> 
>> wrote:
>>
>>> Dear Nihar,
>>>
>>> I am not a CP2K expert but I guess you definitely should use either the 
>>> LSD keyword or one of its synonyms (e.g. SPIN_POLARIZED or UKS or some 
>>> further) in the calculations you mentioned. In cases when the number of 
>>> electrons with spin up differs from the number with spin down, such an 
>>> option is necessary in my knowledge. Even if some part of the calculations 
>>> be for systems in a (globally) singlet state, I would apply spin 
>>> polarisation for consistency between the systems under treatment.
>>>
>>> Best
>>> Martin.
>>>
>>> st 26. 7. 2023 o 10:02 Niharendu Choudhury <nihar... at gmail.com> 
>>> napísal(a):
>>>
>>>> Hi CP2K experts,
>>>> I have a system in which a metal ion and water molecules are there.
>>>> My metal ion has different oxidation states and accordingly different 
>>>> number of unpaired electron/s (which gives me different multiplicity). So I 
>>>> have CHARGE and MULTIPLICITY KEYWORDS to specify these two in the input 
>>>> file. Then, should I use LSD, if MULTIPLICITY is not equal to one?
>>>>
>>>> Can anybody clarify it. 
>>>>
>>>> Regards
>>>> Nihar
>>>>
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>>
>>
>> -- 
>> ---------------------------------------------------------
>> Dr. Niharendu Choudhury 
>> Scientific Officer 
>> Theoretical Chemistry Section
>> Chemistry Group
>> Bhabha Atomic Research Centre
>> Mumbai- 400 085, India.
>> ---------------------------------------------------------
>> Ph: Off: +91-22-2559 5015 <+91%2022%202559%205015>
>> Home  : +91-22-2552 7832 <+91%2022%202552%207832>
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>>
>

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