Calculating expectations with time-dependent perturbations in quantum Monte Carlo.

J Chem Phys

Lawrence Livermore National Laboratory, Livermore, California 94550, USA.

Published: September 2004

We show that a small perturbation periodic in imaginary time can be used to compute expectation values of nondifferential operators that do not commute with the Hamiltonian within the framework of quantum diffusion Monte Carlo. Some results for the harmonic oscillator and the helium atom are presented showing the validity of the proposed method.

Download full-text PDF

Source
http://dx.doi.org/10.1063/1.1783151DOI Listing

Publication Analysis

Top Keywords

monte carlo
8
calculating expectations
4
expectations time-dependent
4
time-dependent perturbations
4
perturbations quantum
4
quantum monte
4
carlo small
4
small perturbation
4
perturbation periodic
4
periodic imaginary
4

Similar Publications

Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis.

J Dairy Sci

January 2025

The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, United Kingdom. Electronic address:

This study investigated the genetics of bovine tuberculosis (bTB) infectivity in Holstein-Friesian dairy cows using British national data. The analyses included cows with recorded sires from herds affected by bTB outbreaks between 2000 and 2022. Animals were considered bTB-positive if they reacted positively to the skin test and/or had positive post-mortem findings.

View Article and Find Full Text PDF

The primary goal of the current work was to construct pH-sensitive nano and microcomposite hydrogel beads based on alginate (AL), carboxymethyl cellulose (CMC), biochar (BC), and two Moroccan clays: Ghassoul (swelling SW) and red (not swelling NSW) nano and microhybrid. The adsorbents, SW + AL, SW + AL + BC, SW + AL + CMC, NSW + AL, NSW + AL + BC, NSW + AL + CMC, AL, and AL + CMC were prepared for the adsorption of the antibiotic sulfadiazine (SDZ). The test samples were characterized using a variety of techniques, including X-Ray Diffraction (XRD), IR spectroscopy (FT-IR), and scanning electron microscopy (SEM), with the molecular structures of the studied additives geometrically optimized using the DFT/B3LYP method and the function 6-311G(d).

View Article and Find Full Text PDF

The abandoned coal in goaf will adsorb the gases ethylene (CH) and acetylene (CH) produced by coal oxidation, which makes the concentration data of the indicator gas inaccurate. Therefore, the adsorption law of coal and CH and CH gas is explored. The macromolecular structure model of coal was established and optimized by simulation, and the gas adsorption process was simulated by means of grand canonical Monte Carlo method.

View Article and Find Full Text PDF

Comparative Study of Polymer Globules and Liquid Droplets in Poor Solvents: Effects of Cosolvents and Solvent Quality.

J Phys Chem B

January 2025

Department of Chemical Engineering, IIT Gandhinagar, Gandhinagar, Gujarat 382055, India.

We compare the structures of polymer globules, composed of flexible polymer chains, with liquid droplets made of nonbonded monomers of the same polymer in poor solvents. This comparison is performed in three different poor solvents, with and without the addition of cosolvents. Molecular dynamics simulations are used to analyze the properties of the polymer globules, while semigrand canonical Monte Carlo simulations are used to form metastable liquid droplets of nonbonded monomers through homogeneous nucleation in the same solvents.

View Article and Find Full Text PDF

Background: High-dose-rate (HDR) brachytherapy using Iridium-192 as a radiation source is widely employed in cancer treatment to deliver concentrated radiation doses while minimizing normal tissue exposure. In this treatment, the precision with which the sealed radioisotope source is delivered significantly impacts clinical outcomes.

Purpose: This study aims to evaluate the feasibility of a new four-dimensional (4D) in vivo source tracking and treatment verification system for HDR brachytherapy using a patient-specific approach.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!