Search found 84 matches

by Katharina Doblhoff
Fri Mar 09, 2018 12:45 pm
Forum: The CASINO program
Topic: N2 DMC energy is better then exact
Replies: 10
Views: 28866

Re: N2 DMC energy is better then exact

Also, you can have a fixed node error. If you are not working with the full wave function that gave the reference result in the first place (and I think that the value you cite was obtained by CCSDT), DMC may well also give an energy that is higher than the value from the "standard" quantu...
by Katharina Doblhoff
Fri Nov 10, 2017 6:13 pm
Forum: The CASINO program
Topic: gjastrow and cutoffs
Replies: 5
Views: 15485

Re: gjastrow and cutoffs

Hi Pablo! Thank you for your explanation. So one could only get a speedup if both e-e term and e-e-n term had a small cutoff, right? And implementing that makes little sense since the e-e term should usually spread over the entire system and will usually also require the highest powers of r^n. Corre...
by Katharina Doblhoff
Fri Nov 10, 2017 4:22 pm
Forum: The CASINO program
Topic: gjastrow and cutoffs
Replies: 5
Views: 15485

Re: gjastrow and cutoffs

Hi Pablo! thank you for your reply! The cutoff is indeed checked here, but still T(Jast only e-e term, large cutoff length) - Ts(no Jast) = T(Jast only e-e term, small cutoff length) - Ts(no Jast) Since the number of electrons within the cutoff radius is proportional to rcut^3, I would expect a clea...
by Katharina Doblhoff
Fri Nov 10, 2017 1:23 pm
Forum: The CASINO program
Topic: gjastrow and cutoffs
Replies: 5
Views: 15485

gjastrow and cutoffs

In my dmc calculations, the presence of a Jastrow factor (gjastrow form) increases the computational time needed for one DMC step by about a factor 2.5. From this I conclude that the evaluation of the MOs plus the determinant update need a computational effort on the same order of magnitude as the c...
by Katharina Doblhoff
Fri Nov 10, 2017 11:02 am
Forum: The CASINO program
Topic: memory requirements in dmc
Replies: 7
Views: 18030

Re: memory requirements in dmc

Hi Mike, For some reason or the other, I still do not get it: I would have thought that there is one array of dimension 50 x 3 x nelectrons x nions... And since (according to the manual) poems count as "shiny things" and since I still want to understand how it works, here comes a limerick ...
by Katharina Doblhoff
Thu Nov 02, 2017 4:48 pm
Forum: The CASINO program
Topic: memory requirements in dmc
Replies: 7
Views: 18030

Re: memory requirements in dmc

@ Pablo Thanks for your answer! I had just figured that out... - stupid me! @ Mike Hang on, I do not get it: How do you get to the 128G per node in the example in the logfile? The array has dimension 50x3x1000x1000. For a double array that is 50x3x1000^2*8B=1.2GB. For 64 processes this makes 77G and...
by Katharina Doblhoff
Thu Nov 02, 2017 3:32 pm
Forum: The CASINO program
Topic: memory requirements in dmc
Replies: 7
Views: 18030

memory requirements in dmc

Dear all, could somebody briefly explain the memory requirements in dmc (when using T-moves)? the reason I am asking is the following: I have a large system with around 1300electrons. It comes fine over the vmc calculations but dies with memory issues when starting the dmc calculations. I have 64GB ...
by Katharina Doblhoff
Fri Sep 08, 2017 5:36 pm
Forum: The CASINO program
Topic: Changing decorr length in vmc for varmin_linjas and emin?!
Replies: 19
Views: 38606

Re: Changing decorr length in vmc for varmin_linjas and emin

Hi Ryan! To keep backward compatibility, I would not take the if statement out. Instead, I would make sure the code does what it is supposed to do. It is stated explicitly in the manual that the decorr period is adapted, such that write statements are separated by the decorr period if vmc_nconfigs_w...
by Katharina Doblhoff
Fri Sep 08, 2017 3:29 pm
Forum: The CASINO program
Topic: Changing decorr length in vmc for varmin_linjas and emin?!
Replies: 19
Views: 38606

Re: Changing decorr length in vmc for varmin_linjas and emin

Found the problem! And this is actually an issue! OK, so, I had vmc_nstep=250000, vmc_configs_write=100000 and vmc_decorrelation_period=24. Thus nwrsteps=2 and corper=24 (sorry, I had a mistake here in an earlier post) Thus corper (or vmc_decorr_period) is reset to 24/2=12 in the first iteration. (a...