[CP2K-user] [CP2K:19434] Re: Questions on the use of the WFN_MIX function to obtain the open-shell singlet state

[John Zhang]

Dear Prof. Lannuzzi

The quintet state has 4 singly occupied alpha spin orbitals. I tried to 
flip two of these alpha spin orbitals to beta spin. therefore, I set the 
"RESULT_MO_INDEX" as negtive to represent the unoccupied MO space. I 
actually also tries the opposite way: setting ORIG_MO_INDEX as the virtual 
MO and RESULT_MO_INDEX as HOMO and HOMO-1. This run was "successful", 
however, I am not sure I understand the results. The output file shows that 
"Performing wfn mixing and Writing new MOs to file" at the end of the 
calculation. In this specific calculation, the spin multiplicity is 5 and I 
used the ATOMIC guess, the program seems to perform wfn mixing after SCF 
for the initial quintet state (although not converge), How do i know the 
wfn mixing is correctly performed? Does the saved wfn file contains the 
spin-fliped singlet state? Could you please provide some suggestions? Thank 
you! Attached please find the input and output.

 

Best wishes

 

John

On Thursday, October 26, 2023 at 4:54:26 AM UTC-4 Marcella Iannuzzi wrote:

> Dear Peng
>
> But why have you set ORIG_IS_VIRTUAL as FALSE and given negative indexes 
> to the MOs?
>
> Regards
> Marcella
>
> On Tuesday, October 24, 2023 at 6:37:10 PM UTC+2 John Zhang wrote:
>
>> Dear Prof. Lannuzzi
>>
>> The previous quintet calculation did not have the "ADDED_MOS". Using 
>> ATOMIC guess, I have MO_CUBES in the PRINT section of DFT, but got the same 
>> error. Please see attached outputs (I did not include the generated cube 
>> files). I am using 2023.2. Maybe my compilation have some issues? or should 
>> I try other version of cp2k? Thanks!
>>
>> Best wishes
>>
>> Peng
>>
>>
>> On Tuesday, October 24, 2023 at 11:45:52 AM UTC-4 Marcella Iannuzzi wrote:
>>
>>>
>>> Dear John, 
>>>
>>> The restart does not work if the previous calculation had ADDED_MOS, but 
>>> the ATOMIC guess should work. 
>>> You have to keep the MO_CUBES in the PRINT section of DFT
>>> It works for me. 
>>>
>>> Regards
>>> Marcella
>>>
>>>
>>>
>>> On Tuesday, October 24, 2023 at 4:51:09 PM UTC+2 John Zhang wrote:
>>>
>>>> Dear Dr Lannuzzi
>>>>
>>>> Thank your for your response!
>>>>
>>>> Following you suggestions, I performed a few test calculations (without 
>>>> the ADDED_MOS)
>>>>
>>>> 1. Starting from the ATOMIC guess with singlet spin multiplicity. The 
>>>> calculation stopped at the beginning of "Performing wfn mixing" and the 
>>>> error message looks like (I pasted only a few lines) 
>>>> "PBLAS ERROR 'Array subscript out of bounds: JX = 7, DESCX[N_] = 4'
>>>> from {0,7}, pnum=7, Contxt=0, in routine 'PDCOPY'.
>>>> PBLAS ERROR 'Parameter number 4 had an illegal value'
>>>> from {0,7}, pnum=7, Contxt=0, in routine 'PDCOPY'.
>>>> {0,7}, pnum=7, Contxt=0, killed other procs, exiting with error #-4.
>>>> "
>>>>
>>>> 2. if the calculation started using the quintet wave function, it 
>>>> immediately stopped and the error message is "Number of occupied MOs on 
>>>> restart unit larger than allocated MOs"
>>>>
>>>> I also checked the examples in the tests, but I cannot figure out what 
>>>> the problem is. Any insight? Thank you again!
>>>>
>>>> Best wishes
>>>>
>>>> John
>>>> On Tuesday, October 24, 2023 at 7:10:30 AM UTC-4 Marcella Iannuzzi 
>>>> wrote:
>>>>
>>>>> Dear John
>>>>>
>>>>> I think that your input might work if you remove the key ADDED_MOS 
>>>>> from SCF.
>>>>> Anyway, the input structure for wfn_mix has slightly changed in most 
>>>>> recent version of the code. 
>>>>>
>>>>> Regards
>>>>> Marcella
>>>>>
>>>>>
>>>>> On Saturday, October 21, 2023 at 7:52:11 PM UTC+2 John Zhang wrote:
>>>>>
>>>>>> Hi
>>>>>>
>>>>>> I want to obtain an open-shell singlet state wave function for a C2 
>>>>>> molecule using the WFN_MIX function. I first performed a quintet state 
>>>>>> calculation (converged smoothly) and tried to use this quintet state wave 
>>>>>> function as the initial guess in the following open-shell singlet state 
>>>>>> calculation. In the WFN_MIX section, I tried to flip the spin of the 
>>>>>> original HOMO and HOMO-1 orbitals (Also see the attached input)
>>>>>>
>>>>>>     &WFN_MIX
>>>>>>
>>>>>>       &UPDATE
>>>>>>
>>>>>>         RESULT_MO_INDEX    -1
>>>>>>
>>>>>>         RESULT_SPIN_INDEX  BETA
>>>>>>
>>>>>>         RESULT_SCALE       0.00000
>>>>>>
>>>>>>
>>>>>>         ORIG_MO_INDEX      2
>>>>>>
>>>>>>         ORIG_SPIN_INDEX    ALPHA
>>>>>>
>>>>>>         ORIG_SCALE         1.0000
>>>>>>
>>>>>>
>>>>>>         ORIG_IS_VIRTUAL    .FALSE.
>>>>>>
>>>>>>       &END UPDATE
>>>>>>
>>>>>>
>>>>>>       &UPDATE
>>>>>>
>>>>>>         RESULT_MO_INDEX    -2
>>>>>>
>>>>>>         RESULT_SPIN_INDEX  BETA
>>>>>>
>>>>>>         RESULT_SCALE       0.00000
>>>>>>
>>>>>>
>>>>>>         ORIG_MO_INDEX      1
>>>>>>
>>>>>>         ORIG_SPIN_INDEX    ALPHA
>>>>>>
>>>>>>         ORIG_SCALE         1.0000
>>>>>>
>>>>>>
>>>>>>         ORIG_IS_VIRTUAL    .FALSE.
>>>>>>
>>>>>>       &END UPDATE
>>>>>>
>>>>>>     &END WFN_MIX
>>>>>>
>>>>>>
>>>>>> but the calculation failed with an error message "If ORIG_IS_VIRTUAL 
>>>>>> is set, the array unoccupied_orbs must be associated!"
>>>>>>
>>>>>> I think my usage of WFN_MIX is not correct. Could someone please help 
>>>>>> on this issue? Thanks!
>>>>>>
>>>>>>
>>>>>> Best 
>>>>>>
>>>>>>
>>>>>> John
>>>>>>
>>>>>>
>>>>>>

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