## Search found 109 matches

Thu Mar 16, 2023 11:36 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 10
Views: 25091

### 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...
Thu Mar 09, 2023 11:43 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 10
Views: 25091

### 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'...
Wed Mar 08, 2023 9:53 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 10
Views: 25091

### 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...
Tue Mar 07, 2023 10:07 am
Forum: The CASINO program
Topic: Order for spin-pairs in electron systems
Replies: 3
Views: 23235

### Re: Order for spin-pairs in electron systems

Tue Mar 07, 2023 10:03 am
Forum: Quantum Monte Carlo
Topic: Constrained derivatives.
Replies: 10
Views: 25091

### 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...
Tue Mar 07, 2023 9:46 am
Forum: The CASINO program
Topic: Order for spin-pairs in electron systems
Replies: 3
Views: 23235

### 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...
Sun Sep 25, 2022 2:47 pm
Forum: Quantum Monte Carlo
Topic: Backtranformed Jastrow
Replies: 1
Views: 2407

### Re: Backtranformed Jastrow

The obvious pitfall in evaluating a Jastrow factor at backflow-transformed quasiparticle coordinates is the need to ensure the Kato cusp conditions are still satisfied. Evaluating a Jastrow factor at backflow transformed coordinates is used in, for example, recursive backflow wave functions after th...
Sat Sep 24, 2022 8:06 pm
Forum: The CASINO program
Topic: molden2qmc
Replies: 44
Views: 133120

### Re: molden2qmc

Thanks very much for maintaining molden2qmc!
Mon May 16, 2022 9:55 am
Forum: Quantum Monte Carlo
Topic: QMC symposium A8 at the 2022 Psi-k conference
Replies: 0
Views: 6803

### QMC symposium A8 at the 2022 Psi-k conference

Dear All,

Please consider submitting an abstract for the QMC symposium at the 2022 Psi-k conference in Lausanne. See https://www.psik2022.net/program/symposia. The deadline for early-bird registration is the 31st of May.

Best wishes,

Neil.
Fri Jan 28, 2022 10:58 am
Forum: The CASINO program
Topic: Stat inefficiency
Replies: 7
Views: 6994

### Re: Stat inefficiency

The Hartree-Fock nodes in the Be atom can easily be shown to be qualitatively wrong. However, since nodes for most other systems are also qualitatively wrong, I'm not sure why the Be atom should necessarily be so much worse. I'm not sure why you say that backflow between same-spin electrons is usele...