Fundamental gap of fluorographene by many-body GW and fixed-node diffusion Monte Carlo methods

2020 ◽  
Vol 153 (18) ◽  
pp. 184706
Author(s):  
Matúš Dubecký ◽  
František Karlický ◽  
Stanislav Minárik ◽  
Lubos Mitas
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
Many Body ◽  
Diffusion Monte Carlo ◽  
Fixed Node

Quantifying electron-correlation effects in small coinage-metal clusters by ab initio calculations

2021 ◽  
Author(s):  
Victor Giovanni de Pina ◽  
Bráulio Gabriel Alencar Brito ◽  
Guo -Q Hai ◽  
Ladir Cândido
Keyword(s):  
Monte Carlo ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Metal Clusters ◽  
Correlation Effects ◽  
Diffusion Monte Carlo ◽  
Coinage Metal ◽  
Electron Correlation Effects ◽  
Fixed Node

We investigate many-electron correlation effects in neutral and charged coinage-metal clusters Cun, Agn, and Aun (n = 1 − 4) by ab initio calculations using fixed-node diffusion Monte Carlo (FN-DMC)...

scholarly journals Toward a systematic improvement of the fixed-node approximation in diffusion Monte Carlo for solids—A case study in diamond

2020 ◽  
Vol 153 (18) ◽  
pp. 184111
Author(s):  
Anouar Benali ◽  
Kevin Gasperich ◽  
Kenneth D. Jordan ◽  
Thomas Applencourt ◽  
Ye Luo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Diffusion Monte Carlo ◽  
Systematic Improvement ◽  
Fixed Node

scholarly journals QUANTUM MONTE CARLO METHODS FOR NUCLEI AT FINITE TEMPERATURE

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1447-1462 ◽  
Author(s):  
Y. ALHASSID
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
Finite Temperature ◽  
Quantum Monte Carlo ◽  
Configuration Spaces ◽  
Many Body ◽  
Level Densities ◽  
Sign Problem ◽  
Quantum Monte Carlo Methods ◽  
Nuclear Shell

We discuss finite temperature quantum Monte Carlo methods in the framework of the interacting nuclear shell model. The methods are based on a representation of the imaginary-time many-body propagator as a superposition of one-body propagators describing non-interacting fermions moving in fluctuating auxiliary fields. Fermionic Monte Carlo calculations have been limited by a "sign" problem. A practical solution in the nuclear case enables realistic calculations in much larger configuration spaces than can be solved by conventional methods. Good-sign interactions can be constructed for realistic estimates of certain nuclear properties. We present various applications of the methods for calculating collective properties and level densities.

scholarly journals A FOURTH ORDER DIFFUSION MONTE CARLO ALGORITHM FOR SOLVING QUANTUM MANY-BODY PROBLEMS

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1752-1755 ◽  
Author(s):  
H. A. FORBERT ◽  
S. A. CHIN
Keyword(s):  
Monte Carlo ◽  
Fourth Order ◽  
Planck Equation ◽  
Monte Carlo Algorithm ◽  
Bulk Liquid ◽  
Many Body ◽  
Diffusion Monte Carlo ◽  
Step Size ◽  
Wide Range ◽  
Gaussian Random Walk

We derive a fourth-order diffusion Monte Carlo algorithm for solving quantum many-body problems. The method uses a factorization of the imaginary time propagator in terms of the usual local energy E and Langevin operators L as well as an additional pseudo-potential consisting of the double commutator [EL, [L, EL]]. A new factorization of the propagator of the Fokker-Planck equation enables us to implement the Langevin algorithm to the necessary fourth order. We achieve this by the addition of correction terms to the drift steps and the use of a position-dependent Gaussian random walk. We show that in the case of bulk liquid helium the systematic step size errors are indeed fourth order over a wide range of step sizes.

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