# Tag Info

12

"However, it is notorious due to the exponential wall" That is completely true, though there's indeed some methods such as FCIQMC, SHCI, and DMRG that try to mitigate this: How to overcome the exponential wall encountered in full configurational interaction methods?. The cost of FCIQMC still scales exponentially with respect to the number of ...

8

Quantum Monte Carlo (QMC) calculations in various forms, for example variational QMC or diffusion QMC have been used to study periodic systems for decades. In most cases, they provide results that are more accurate than DFT, so it is often taken as a reference for solid state calculations. Indeed, the pioneering QMC calculations of the electron gas by ...

7

Conventional implementations of Kohn-Sham DFT scale cubically with system size. This is principally because at some point they: orthonormalise a set of $N$ trial states, each expressed in a basis comprising $M$ basis states; this has a computational cost $O(MN^2)+O(N^3)$ diagonalise a dense Hamiltonian matrix in the subspace of $N$ trial states, which has ...

4

This question is a bit old now, but hopefully my answer can complement Thomas's for anyone who comes across it. While "materials" is not in the name of the book, I think great (though more advanced) introductions to these topics can be found in Thijssen's Computational Physics. What's nice about it is that it covers the theory, provides coding (as ...

3

NECI (N-electron configuration interaction solver) This is a free and open-source software written mainly in FORTRAN but with components in C/C++ and Python. It has been shown on a FeMoco calculation to have a parallelization efficiency of 99.7% up to at least 24800 cores. It does FCIQMC and has been used on Hubbard models in several papers, perhaps the most ...

2

ALF (Algorithms for Lattice Fermions) This is an auxiliary-field quantum Monte Carlo package. It's free, open-source, actively maintained (current version: 2.0, with 2.1 on the works — news are posted on its website) and has been cited in dozens of publications since its release in 2017. The package is very flexible, as it can simulate any Hamiltonian that ...

1

Advantage for QMC: While this question is quite open ended due to there being at least 15 different types of QMC, one thing that all 15 of those methods have in common is that as far as I know they can all be restarted when the calculation has to stop for whatever reason. Since you pointed out that ACFDT-RPA calculations cannot be restarted, the ability to ...

Only top voted, non community-wiki answers of a minimum length are eligible