...density
It was shown by Harriman[12] that all densities are N-representable
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...choice
The choice of g(x)=|f(x)| minimises the variance of the estimate of the integral
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...energy,
For silicon the total energy per atom is of the order of -107eV and the contribution from the non-local part of the pseudopotential is of the order of 2eV per atom (with p local).
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...itself.
The fixed-node approximation does depend on the guiding wavefunction. None of the optimisation here changes the nodal structure because the Slater determinant is not being optimised.
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...N
In the limit of an infinitely large simulation cell the residual value of the CFSE reflects the fact that different choices of the boundary conditions at infinity give total energies which differ by a finite amount.
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...hole
Calculations of pair correlation functions [74] show they converge rapidly with simulation cell size.
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...approximation
Note that a successful QMC calculation requires a reasonable approximation to the wavefunction itself, so that the requirement of a reasonable approximation to the charge density is not a serious limitation.
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...affinity
Strictly, the electron affinity of the N electron system is defined as 597#597
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...it
This is achieved by reducing the distances to all the other electrons into the Wigner-Seitz cell centred on the electron being considered.
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```

Andrew Williamson
Tue Nov 19 17:11:34 GMT 1996