Questions tagged [quantum-monte-carlo]

Questions related with quantum Monte Carlo methods.

Filter by
Sorted by
Tagged with
16 votes
2 answers
2k views

How to explain to a five year old why "DFT with local exchange–correlation functionals do(es) not describe van der Waals interactions accurately"?

From How do you explain Canada's Trudeau's power-sharing agreement to a five-year-old (American)?: The "explain to a five-year-old" question is a semi-standard format where the answer ...
user avatar
  • 1,962
17 votes
1 answer
747 views

Deep Neural Networks: Are they able to provide insights for the many-electron problem or DFT?

The solution of the many-electron Schrodinger equation is the key to understand the properties of matter. However, it is notorious due to the exponential wall (for example, see section II (C) of ...
user avatar
  • 13.9k
7 votes
1 answer
131 views

What are the advantages/disadvantages of QMC over ACFDT-RPA?

I had some experience with the ACFDT-RPA, but despite its promising features it's not practical most of the time, and for that reason, I'm looking for a new method for reference calculations. QMC is ...
user avatar
  • 1,859
10 votes
1 answer
197 views

Are QMC calculations practical for periodic structure calculations?

Even some DFT methods or beyond DFT methods such as MP2 calculations are computationally very expensive today even with clusters. If you compare QMC (quantum monte carlo) calculations with them, are ...
user avatar
  • 1,859
7 votes
1 answer
91 views

Support for orbital-space Quantum Monte Carlo in CASINO?

Is CASINO code capable of performing orbital-space QMC calculations?
user avatar
9 votes
2 answers
117 views

What packages exist for building quantum Monte Carlo simulations of spin or Hubbard Hamiltonians?

What packages exist that can help someone, especially a new masters/PhD student get started with QMC on spin or Hubbard systems? As an example, for writing a stochastic series expansion QMC program ...
user avatar
14 votes
2 answers
152 views

Order of scaling for different algorithms

There are many different computational methods used in matter modelling. For example: solving multi-electron Schroedinger equation, DFT with different approximations, Quantum Monte Carlo, etc. How ...
user avatar
  • 8,402
13 votes
3 answers
308 views

What are the types of Quantum Monte Carlo?

Similar to: What are the types of SCF? What are the types of MCSCF? What are the types of ab initio Molecular Dynamics? What are the types of pseudopotentials? What are the types of DFT? What are the ...
user avatar
  • 28.8k
37 votes
1 answer
2k views

Was Walter Kohn wrong about this?

In Kohn's Nobel Lecture, he claimed that: "In general the many-electron wave function $\Psi(\mathbf{r}_1,\ldots,\mathbf{r}_N)$ for a system of $N$ electrons is not a legitimate scientific concept,...
user avatar
  • 10.4k
14 votes
1 answer
95 views

How accurately are magnetic effects treated in *ab initio* methods?

I am a condensed matter theorist and I mostly use quantum Monte Carlo methods. I use models like the Heisenberg model, an represent an extreme simplification of real materials to just localized spin ...
user avatar
12 votes
0 answers
235 views

How to understand dynamical spin structure factor? [closed]

A newish area of interactions between quantum Monte Carlo (QMC) and experiments is in spin spectra. Recent improvements in stochastic analytic continuation have made it much easier to compare/extract ...
user avatar
20 votes
1 answer
126 views

How can very small lattices be sufficient for Quantum Monte Carlo simulations?

Quantum Monte Carlo simulations are often performed with very modest lattice sizes (such as [e-print], $64$ sites), due to their computational cost increasing exponentially with the system volume; ...
user avatar
  • 786
12 votes
2 answers
476 views

Autocorrelation function problem in Monte Carlo simulation of 2D Ising model

Currently, I did a Monte Carlo simulation with the local update and Wolff cluster updated in 2D classical Ising model. I use the autocorrelation function to compare 2 different algorithm in critical ...
user avatar
  • 2,723
16 votes
2 answers
87 views

Is there a list of models that do and do not have the QMC sign problem?

The sign problem is a huge limitation of QMC, but it's not easy to tell by looking at a Hamiltonian if it has the sign problem. Often there will be some clever transformation that allows you to avoid ...
user avatar
13 votes
2 answers
412 views

What are good resources to learn Materials Modeling?

I wonder if there are any books or resources to start learning Materials modelling using methods density functional theory quantum monte carlo molecular dynamics
user avatar
  • 1,001
25 votes
1 answer
162 views

Is there a "gold standard" method in materials modeling for obtaining ground state energy?

In quantum chemistry, coupled-cluster methods, especially CCSD(T), with complete basis set extrapolation are often considered a "gold-standard" for closed-shell molecules. This means that we consider ...
user avatar
  • 1,648
21 votes
1 answer
89 views

QMC calculation of the equation of state of metals

Is diffusion/variational quantum Monte Carlo applicable to the calculation of the athermal (zero temperature, no zero point energy) equation of state of metals including electronic correlation? For ...
user avatar
  • 413