scholarly journals Pseudo-BCS wave function from density matrix decomposition: Application in auxiliary-field quantum Monte Carlo

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Zhi-Yu Xiao ◽  
Hao Shi ◽  
Shiwei Zhang
Keyword(s):  
Monte Carlo ◽  
Wave Function ◽  
Density Matrix ◽  
Quantum Monte Carlo ◽  
Matrix Decomposition ◽  
Auxiliary Field

scholarly journals Extraction of a One-Particle Reduced Density Matrix from a Quantum Monte Carlo Electronic Density: A New Tool for Studying Nondynamic Correlation

Computation ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 135
Author(s):  
Carmelo Naim ◽  
Claudio Amovilli
Keyword(s):  
Monte Carlo ◽  
Wave Function ◽  
Density Matrix ◽  
Quantum Monte Carlo ◽  
Valence Bond ◽  
Reduced Density Matrix ◽  
Electronic Density ◽  
Complete Active Space ◽  
Energy Functionals ◽  
Reduced Density

In this work, we present a method to build a first order reduced density matrix (1-RDM) of a molecule from variational Quantum Monte Carlo (VMC) computations by means of a given correlated mapping wave function. Such a wave function is modeled on a Generalized Valence Bond plus Complete Active Space Self Configuration Interaction form and fits at best the density resulting from the Slater-Jastrow wave function of VMC. The accuracy of the method proposed has been proved by comparing the resulting kinetic energy with the corresponding VMC value. This 1-RDM is used to analyze the amount of correlation eventually captured in Kohn-Sham calculations performed in an unrestricted approach (UKS-DFT) and with different energy functionals. We performed test calculations on a selected set of molecules that show a significant multireference character. In this analysis, we compared both local and global indicators of nondynamic and dynamic correlation. Moreover, following the natural orbital decomposition of the 1-RDM, we also compared the effective temperatures of the corresponding Fermi-like distributions. Although there is a general agreement between UKS-DFT and VMC, we found the best match with the functional LC-BLYP.

scholarly journals Auxiliary-field quantum Monte Carlo calculations of the molybdenum dimer

2016 ◽  
Vol 144 (24) ◽  
pp. 244306 ◽  
Author(s):  
Wirawan Purwanto ◽  
Shiwei Zhang ◽  
Henry Krakauer
Keyword(s):  
Monte Carlo ◽  
Quantum Monte Carlo ◽  
Auxiliary Field ◽  
Monte Carlo Calculations
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