scholarly journals Full Wave Function Optimization with Quantum Monte Carlo and Its Effect on the Dissociation Energy of FeS

2017 ◽  
Vol 121 (32) ◽  
pp. 6165-6171 ◽  
Author(s):  
Kaveh Haghighi Mood ◽  
Arne Lüchow
Keyword(s):  
Monte Carlo ◽  
Wave Function ◽  
Dissociation Energy ◽  
Quantum Monte Carlo ◽  
Function Optimization ◽  
Full Wave

Wave function optimization with a fixed sample in quantum Monte Carlo

1990 ◽  
Vol 93 (5) ◽  
pp. 3326-3332 ◽  
Author(s):  
Zhiwei Sun ◽  
Sheng‐yu Huang ◽  
Robert N. Barnett ◽  
William A. Lester
Keyword(s):  
Monte Carlo ◽  
Wave Function ◽  
Quantum Monte Carlo ◽  
Function Optimization ◽  
Fixed Sample

scholarly journals Diffusion and Reptation Quantum Monte Carlo Study of the NaK Molecule

2018 ◽  
Author(s):  
Marc E. Segovia ◽  
Oscar Ventura
Keyword(s):  
Monte Carlo ◽  
Dipole Moment ◽  
Potential Energy ◽  
Dissociation Energy ◽  
Quantum Monte Carlo ◽  
Density Functional ◽  
Basis Set ◽  
Energy Curve ◽  
Dft Methods ◽  
Trial Wavefunction

<p>Diffusion Monte Carlo (DMC) and Reptation Monte Carlo (RMC) methods, have been applied to study some properties of the NaK molecule. Hartree-Fock (HF), Density Functional (DFT) and single and double configuration interaction (SDCI) wavefunctions with a valence quadruple zeta atomic natural orbital (VQZ/ANO) basis set were used as trial wavefunctions. Values for the potential energy curve, dissociation energy and dipole moment were calculated for all methods and compared with experimental results and previous theoretical derivations. Quantum Monte Carlo (QMC) calculations were shown to be useful methods to recover correlation in NaK, essential to obtain a reasonable description of the molecule. The equilibrium distance—interpolated from the potential energy curves—yield a value of 3.5 Å, in agreement with the experimental value. The dissociation energy, however, is not as good. In this case, a conventional CCSD(T) calculation with an extended aug-pc-4 basis set gives a much better agreement to experiment. On the contrary, the CCSD(T), other MO and DFT methods are not able to reproduce correctly the large dipole moment of this molecule. Even DMC methods with a simple HF trial wavefunction are able to give a better agreement to experiment. RMC methods are even better, and the value obtained with a B3LYP trial wavefunction is very close to the experimental one.</p>

Quantum Monte Carlo calculations of the dissociation energy of the water dimer

2006 ◽  
Vol 125 (10) ◽  
pp. 104302 ◽  
Author(s):  
N. A. Benedek ◽  
I. K. Snook ◽  
M. D. Towler ◽  
R. J. Needs
Keyword(s):  
Monte Carlo ◽  
Dissociation Energy ◽  
Quantum Monte Carlo ◽  
Water Dimer ◽  
Monte Carlo Calculations

scholarly journals OPTIMIZATION OF QUANTUM MONTE CARLO WAVE FUNCTION: STEEPEST DESCENT METHOD

2010 ◽  
Vol 21 (04) ◽  
pp. 523-533 ◽  
Author(s):  
M. EBRAHIM FOULAADVAND ◽  
MOHAMMAD ZARENIA
Keyword(s):  
Monte Carlo ◽  
Wave Function ◽  
Quantum Monte Carlo ◽  
Descent Method ◽  
Steepest Descent ◽  
Steepest Descent Method ◽  
Direct Energy Minimization ◽  
Direct Energy ◽  
Spatial Coordinates ◽  
Quantum Monte Carlo Method

We have employed the steepest descent method to optimize the variational groundstate quantum Monte Carlo wave function for He , Li , Be , B and C atoms. We have used both the direct energy minimization and the variance minimization approaches. Our calculations show that in spite of receiving insufficient attention, the steepest descent method can successfully minimize the wave function. All the derivatives of the trial wave function respect to spatial coordinates and variational parameters have been computed analytically. Our groundstate energies are in a very good agreement with those obtained with diffusion quantum Monte Carlo method (DMC) and the exact results.

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