The CASINO forum

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...

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'...

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...

I keep losing my replies and having to log out and log in again. I'll ask Mike about it.

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...

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...

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...

Thanks very much for maintaining molden2qmc!

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.

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...