Search found 113 matches

by Neil Drummond
Mon Jan 15, 2024 3:26 pm
Forum: The CASINO program
Topic: Nitrogen molecule with PP and AE atoms.
Replies: 8
Views: 2353

Re: Nitrogen molecule with PP and AE atoms.

Does the trick of looking at a N"P" (nitrogen "phosphide") molecule, where the nitrogen is all-electron and the phosphorus is actually a pseudonitrogen atom not work?

Best wishes,

Neil.
by Neil Drummond
Mon Jan 15, 2024 11:47 am
Forum: The CASINO program
Topic: Nitrogen molecule with PP and AE atoms.
Replies: 8
Views: 2353

Re: Nitrogen molecule with PP and AE atoms.

CASINO allows you to have both all-electron and pseudopotential ions present. For an example, see CASINO/examples/molecule/silane/ground_state which has a silicon pseudopotential, while the hydrogen atoms are all-electron. Before 2014 there used to be a mishmash of CASINO keywords related to allowin...
by Neil Drummond
Sun Jan 14, 2024 10:21 pm
Forum: The CASINO program
Topic: Nitrogen molecule with PP and AE atoms.
Replies: 8
Views: 2353

Re: Nitrogen molecule with PP and AE atoms.

Perhaps you could look at a "nitrogen phosphide" molecule, where the nitrogen is all electron (no n_pp.data file is supplied) and the phosphorus pseudopotential in p_pp.data is actually just a renamed nitrogen pseudopotential? To create this p_pp.data file you could just rename n_pp.data a...
by Neil Drummond
Mon Dec 18, 2023 11:42 am
Forum: Quantum Monte Carlo
Topic: Goodhart's law and VMC optimization.
Replies: 2
Views: 13519

Re: Goodhart's law and VMC optimization.

Dear Vladimir, Is your point that, for example, VMC variance isn't a perfect measure for comparing two different types of wave function when they are optimised by minimising the variance? Or is your point that we optimise wave functions by some criterion that stands in for the one we are ultimately ...
by Neil Drummond
Thu Mar 16, 2023 11:36 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 9
Views: 53979

Re: Constrained derivatives.

Sorry it has taken me ages to reply. Analytical derivatives w.r.t. backflow parameters will certainly get messy. Obviously I agree that you can evaluate linearly constrained derivatives for parameters by evaluating unconstrained derivatives and using linear algebra. This could be done using the proj...
by Neil Drummond
Thu Mar 09, 2023 11:43 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 9
Views: 53979

Re: Constrained derivatives.

An alternative approach for dealing with the homogeneous linear constraints would be to use SVD to find the basis spanning the nullity (the solution space) and then the parameters in correlation.data would be the coefficients of those basis vectors, again giving an independent set of parameters. It'...
by Neil Drummond
Wed Mar 08, 2023 9:53 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 9
Views: 53979

Re: Constrained derivatives.

For the "old" Jastrow factor in pjastrow.f90, the subroutine "get_linear_basis" returns analytical derivatives w.r.t. the independent subset of linear parameters. At present this is only used in the "varmin-linjas" optimisation method, however. Numerical differentiation...
by Neil Drummond
Tue Mar 07, 2023 10:07 am
Forum: The CASINO program
Topic: Order for spin-pairs in electron systems
Replies: 3
Views: 59040

Re: Order for spin-pairs in electron systems

I keep losing my replies and having to log out and log in again. I'll ask Mike about it.
by Neil Drummond
Tue Mar 07, 2023 10:03 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 9
Views: 53979

Re: Constrained derivatives.

In CASINO we have (so far) dealt with constraints by using them to eliminate parameters, leaving us with an independent set of parameters. For simple things like the u ( r ) term in the Jastrow factor it is easy enough to express the coefficient of the first-order term in terms of the zeroth-order t...
by Neil Drummond
Tue Mar 07, 2023 9:46 am
Forum: The CASINO program
Topic: Order for spin-pairs in electron systems
Replies: 3
Views: 59040

Re: Order for spin-pairs in electron systems

Dear Vladimir, The spin-dependence options, with their precise groupings and orderings, can be found in the out file at Particle-pair groupings ----------------------- Spin-pair dep. 0 : (1-1,1-2,2-2) Spin-pair dep. 1 : (1-1,2-2) (1-2) Spin-pair dep. 2 : (1-1) (1-2) (2-2) The above is for an electro...