## Indexes in correlation.data file

General discussion of the Cambridge quantum Monte Carlo code CASINO; how to install and setup; how to use it; what it does; applications.
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Joined: Wed Apr 15, 2015 3:14 pm

### Indexes in correlation.data file

Hi all.
My question is about correlation.data file.

I find detailed explanation about JASTRO factor used for finit system and placed in correlation.data file. https://arxiv.org/pdf/0801.0378.pdf
In formulas (19), (20), (21) alpha, beta, gamma have 1, 2 and 4 indexes respectively, but in correlation.data I have found next lines

7.5982746075803145E-003 1 ! alpha_0,1
1.3426533565298453E-002 1 ! alpha_0,2
-7.2944837829337049E-003 1 ! beta_0,1,1

-2.4907681898067393E-003 1 ! gamma_1,1,0,1,1
3.5449418331906443E-003 1 ! gamma_2,1,0,1,1
2.1243610924541823E-003 1 ! gamma_2,2,0,1,1
-3.2040038712909851E-004 1 ! gamma_0,0,2,1,1
-1.2600199356446610E-003 1 ! gamma_1,0,2,1,1
-1.2640600490430177E-003 1 ! gamma_1,1,2,1,1
5.9060512214081267E-004 1 ! gamma_2,1,2,1,1
What is the correspondence between the indices in formulas and file and what are the extra index for?

Thank you in advance for answering my simple question.

In Soviet Russia Casino plays you.
Ryan_Hunt
Posts: 26
Joined: Thu Mar 10, 2016 10:58 am
Location: Lancaster, UK

### Re: Indexes in correlation.data file

The final index for alpha, and the second-to-last indices for beta and gamma are the "spin-pair-type" indices. If one allows for a spin dependence of the corresponding terms in the Jastrow exponent, then these indices may differ from each other (e.g. if you make the simple choice of setting spin dependence uu=dd=/=ud, you will find alpha terms with final indices of both "1" and "2", and of course there will be twice as many optimisable parameters in this case).

The final indices for beta and gamma are the "ion set". For example, if the gamma or beta coefficients appear in "SET 1" blocks, the final index will always be "1". If they appeared in a "SET 2" block, they will always read "2", etc. This is common if one studies a system made up of more than one kind of atom (where one would presumably want to specify different Jastrow terms for each!)

Regards,
Ryan.