Quantum Chem. A , , 38 , , DOI: Reviews , , 25 , , DOI: Hariharan, P. Matta, C. Theochem , , , , DOI: Mass Spectrom. Schaefer III, H. Sen, K.
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Soulsby, D. Faraday Soc. Data , , 14 , , DOI: B: Struct. Dykstra, C. Data , , 27 , , DOI: Press: Ithaca, NY, Knight, J. B , , 37 , , DOI: Data , , 17 S1 , Phys , , 3 , Resumed , , 0 , , DOI: A , , 16 , , DOI: Evans, M. Leszczynski, J. WI, Madison, c. Cyclopropane, bicyclo[1. Acta , , 68 , , DOI: Raman Spectrosc. Durig, J. Press: Oxford, , pp. By constructing a series of water models, these DIFF models, are shown to be competitive with some of the most elaborate water models currently available.
This methodology is general and can be used to derive many-body models for any system. Title: A general linear scaling implementation for polarizable embedding methods. Such a strategy is not only very efficient, allowing for the treatment of very large embeddings, but also completely general, as it is in principle able to deal with arbitrary order static multipoles and different polarization models.
Title: Relativistic coupled cluster for a new generation of supercomputers. Synopsis: I will present a new implementation of relativistic coupled cluster algorithms that is based on the efficient GPU-adapted and parallel ExaTensor library of Lyakh. I will discuss our design choices, required starting data, present capabilities and performance of the code.
I will also give an outlook of our possible further developments. Title: From molecular properties to intermolecular interaction potentials.remontrvd.com/libraries/164-chloroquine-phosphate.php
Quantum Theory Project - University of Florida
Synopsis: It will be shown that if molecular properties of monomers are properly distributed among atoms, the resulting asymptotic expansions of interaction energies provide an excellent approximation of these energies down to intermonomer separations about 1. This finding is important for development of intermolecular force fields both from first principles and in semiepirical ways. Title: Scalable polarizable molecular dynamics using Tinker-HP. Title: Relativistic equation of motion coupled cluster based on four-compoment Hamiltonians. We showcase the method with calculations of low-lying electronic states of halogen monoxides, excited and ionized of the plutonium dioxide molecule, and ionization energies of halide-water droplets systems.
Title: Intermolecular interaction energies from fourth order many-body perturbation theory. Impact of individual electron correlation contributions. Synopsis: The performance of Moller-Plesset perturbation theory methods for describing intermolecular interaction energies is investigated with the focus on illuminating the impact of individual electron correlation energy contributions in fourth order.
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I will also discuss our recent efforts towards development of machine learning based polarizable force fields. Title: Relativistic density functional theory with picture-change corrected electron density. Synopsis: We developed the picture-change corrected PCC relativistic DFT that relies on a unitary-transformed density operator as well as a unitary-transformed Hamiltonian.
Furthermore, we examined the techniques to reduce the computational cost to evaluate the PCC density. In the presentation, I will explain the theoretical aspects s, implementation, and some numerical applications. Are these promises fulfilled? This work examines performance of these new methods in transition-metal chemistry and catalysis.
Synopsis: In this talk, the challenges theoretical chemistry faces when one wants to describe energetics and dynamics of electron transfer in complex heterogeneous media, as proteins, will be discussed. Specifically, the role of environment polarization and long-range electrostatic interactions on the for accurate evaluation such quantities as redox potentials, charge-transfer states excitation energies, and electronic couplings, using a cryptochrome protein as a model system, will be addressed.
Synopsis: An efficient implementation of scalar-relativistic NMR shielding tensors based on the exact two-component theory X2C in the diagonal local approximation to the unitary decoupling matrix DLU is presented. Efficiency and accuracy are demonstrated for heavy-element compounds with more than atoms. Further, extensions for the all-electron relativistic Karlsruhe basis sets are presented and their quality is assessed. Synopsis: We investigate the utility of non-unitary similarity transformations, based on Jastrow or Gutzwiller factorisation of the electronic wavefunction.
Such factorisations generally lead to non-Hermitian effective Hamiltonians which contain three-body interactions.
Such Hamiltonians are treatable via the projective FCIQMC technique, which does not suffer from the non-Hermitian characteristic of the Hamiltonian, nor do the 3-body terms present an insuperable obstacle. Synopsis: We have performed restricted path integral Monte Carlo PIMC simulations for the spin-polarized and unpolarized homogeneous electron gas in two dimension at low densities and low temperatures. We obtain the conditions for stability of the Wigner crystal by directly observing freezing and melting. Synopsis: Ultra-precise computations accounting for non-adiabatic, relativistic, and radiative effects are necessary to understand and make use of ultra-precise measurements of molecular transition energies of sub-MHz uncertainty made possible by recent developments in the experimental control and manipulation of molecular states.
The method has been applied to challenging molecular systems with more than 2 billion variational determinants and trillions of perturbative determinants.
Recent work on improving the efficiency of orbital optimization is described. Title: A path-integral sampling trajectory-free approach to the calculation of quantum time correlation functions. Synopsis: A new path-integral based sampling scheme is presented for the calculation of symmetrized quantum time correlation functions. The approach employs a transformation to sum and difference variables between forward and backward complex-time paths.
It is shown that a formal integration over the difference variables yields an integral over the sum variables with a positive-definite distribution that can be sampled. Approximations to this formal integral are investigated and examples presented. Synopsis: This talk will investigate the efficiency of F12 methods at recovering correlation effects of electrons in the compact inner valence orbitals found in lanthanides and actinides, as well as the important outer-core electrons.
Initial results for geometries and relative energies will be presented at the CCSD T -F12 level of theory using existing cc-pVnZ-PP basis sets for selected uranium-containing molecules. Preliminary design of new F12 basis sets for uranium will also be discussed. Synopsis: We will discuss uses for excited state variational principles across a wide range of electronic structure contexts, including mean field theory, density functional theory, multi-reference theory, and quantum Monte Carlo.
Synopsis: We first show a unified second-order scheme for constructing simple, robust and accurate algorithms for typical thermostats for exact quantum statistics for the canonical ensemble. The scheme consistently improves the efficiency for evaluating all quantum thermodynamic properties. We then show path integral Liouville dynamics PILD that has the two important properties: conserves the quantum canonical distribution and recovers exact thermal correlation functions of even nonlinear operators.
Synopsis: The computational efficiency of local correlation methods is strongly dependent on the size of the domain of functions used to expand local correlating orbitals. Here we define a principal domain of order m as the subset of m one-particle functions that provides the best support for a given n-electron wavefunction. We present a linear scaling greedy algorithm for obtaining principal domains of PAOs and demonstrate its utility in the context of PNO local correlation theory.
Table of contents for issues of Advances in Quantum Chemistry
Synopsis: I will present methods to calculate the electronic structure of challenging systems including metalloenzymes and quantum materials using methods that scale polynomially with the size of the problem. Synopsis: The quantum-classical path integral QCPI offers a rigorous, yet efficient way of combining a quantum mechanical description of a system with a classical trajectory treatment of its complex polyatomic environment without any assumptions or adjustable parameters. Further, a modular decomposition of the path integral MPI allows fully quantum mechanical calculations of coupled electron-vibration dynamics in systems characterized by a quasi-one-dimensional topology with linear scaling.
Title: Explicitly correlated local coupled-cluster methods for large molecules. Synopsis: We review recent developments of explicitly correlated coupled-cluster methods for large closed-shell and open-shell molecules. Benchmark calculations for reaction energies, intermolecular interaction energies, ionization energies, and radical stabilization energies are presented, which demonstrate the outstanding accuracy and efficiency of the methods.
Synopsis: Second-order Moller-Plesset perturbation MP2 theory is one of the simplest approaches to electron correlation but it is difficult to parallelize on large numbers of processing units and its cost scales quintically with the size of the system. We will present a quadrature-based approximation Q-MP2 which is highly parallelizable and whose computational cost grows only quadratically with system size. Title: Molecules driven by light: Electron and nuclear dynamics. Synopsis: In molecules driven by light, electrons and nuclei are set in motion.
In the talk, correlated wavefunction methods will be used to describe post-excitation electron dynamics, time-dependent correlation functions for vibronic spectra, and, finally, non-adiabatic surface hopping techniques for photochemical reactions.
Related Advances in Chemical Physics: Ab Initio Methods in Quantum Chemistry Part 2, Volume 69
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