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Re^7: Facing memory issue in BSSE calculations.

Alex Granovsky

Dear Siddheshwar,

I'm sorry for delay with my reply.

Non-zero NZVAR is not required for hessian runs unless you are
requesting one of PURIFY, PRTIFC, or DECOMP keywords in $FORCE
group, see the description of $FORCE group in the Firefly_input_v2.txt
file which is coming as a part of Firefly's documentation.

Setting NZVAR=0 normally does not speed up hessian computations much
but allows to avoid huge memory allocation requests caused by
automated DLC generation for the pathological cases of very compact 2D
and 3D structures like your typical objects are.

Hope this helps.

Kind regards,
Alex Granovsky

On Tue Feb 21 '17 8:52am, Siddheshwar Chopra wrote
>Dear Alex,
>Thank you for the necessary information. Is non-zero NZVAR required for hessian run? If no, then does making NZVAR=0 speed up the hessian calculations?

>On Mon Feb 20 '17 5:26pm, Alex Granovsky wrote
>>Dear Siddheshwar,

>>at present, DLC generation algorithm in Firefly considers ghost atoms
>>just like regular atoms.  

>>As to DLCs, please take in mind that normally there is a little sense
>>to use DLCs in any computations except for geometry optimization
>>or saddle point location runs! This means that most commonly
>>you need to provide non-zero NZVAR only for these two types of jobs.
>>Otherwise, do not specify NZVAR variable and this will save you a lot of time.

>>Kind regards,
>>Alex Granovsky
>>On Tue Feb 7 '17 7:54am, Siddheshwar Chopra wrote
>>>Dear Alex,
>>>Thank you for taking time for answering my question. No issues at all.
>>>I tried what you have suggested, and it worked well. Thank you for this kind help.
>>>Could you also clarify this? Why didn't FIREFLY give any error related to lesser NZVAR in this case? Is it due to the ghost atoms?

>>>Please help me in getting rid of it.


>>>On Mon Feb 6 '17 6:49pm, Alex Granovsky wrote
>>>>Dear Siddheshwar,

>>>>I'm sorry for delay with my reply.

>>>>You need to set nzvar=0 in $contrl

>>>>Kind regards,
>>>>Alex Granovsky
>>>>On Thu Feb 2 '17 1:05pm, Siddheshwar Chopra wrote
>>>>>Dear Alex,

>>>>>I have sent them to your gmail id. Please have a look at them.


>>>>>On Sun Jan 29 '17 7:04pm, Alex Granovsky wrote
>>>>>>Dear Siddheshwar,

>>>>>>could you please attach sample input and output files?

>>>>>>Kind regards,
>>>>>>Alex Granovsky
>>>>>>On Sat Jan 28 '17 4:08pm, Siddheshwar Chopra wrote
>>>>>>>Dear All,
>>>>>>>This is the first time that I am trying to calculate BSSE corrected energies. Say, I have a system of A+B with A=30 A atoms and B= 1 B atom. Firefly ran properly for E(A)ab, but strangely giving memory error for E(B)ab (notations are as per the manual). Why is this happening? and how to get over it. Please guide me.


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