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Nuclear Energy Gradients for Internally Contracted Complete Active Space Second-Order Perturbation Theory: Multistate Extensions.
TLDR
The theory and computer program for analytical nuclear energy gradients for (extended) multistate complete active space perturbation theory (CASPT2) with full internal contraction is reported, an extension of the fully internally contracted CASPT2 nuclear gradient program recently developed for a state-specific variant.
Fully relativistic complete active space self-consistent field for large molecules: quasi-second-order minimax optimization.
We develop an efficient algorithm for four-component complete active space self-consistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin-orbit and other
Equations of explicitly-correlated coupled-cluster methods.
The tensor contraction expressions defining a variety of high-rank coupled-cluster energies and wave functions that include the interelectronic distances (r(12)) explicitly (CC-R12) have been derived
Canonical transcorrelated theory with projected Slater-type geminals.
TLDR
The present approach constructs a singularity-free Hamiltonian a priori, similarly to the so-called transcorrelated theory, while the use of the canonical transformation assures that the effective Hamiltonian is two-body and Hermite.
Communication: An efficient algorithm for evaluating the Breit and spin-spin coupling integrals.
  • T. Shiozaki
  • Physics, Medicine
    The Journal of chemical physics
  • 15 March 2013
TLDR
An efficient algorithm for evaluating a class of two-electron integrals of the form r12⊗r12/r12(n) over one-electrons Gaussian basis functions is presented, based on tailored Gaussian quadrature, similar to the Rys quadratures for electron repulsion integrals (ERIs), and can utilize the so-called horizontal recurrence relation to reduce the computational cost.
The Fermionic Quantum Emulator
The fermionic quantum emulator (FQE) is a collection of protocols for emulating quantum dynamics of fermions efficiently taking advantage of common symmetries present in chemical, materials, and
Communication: extended multi-state complete active space second-order perturbation theory: energy and nuclear gradients.
TLDR
The extended multireference quasi-degenerate perturbation theory, proposed by Granovsky, is combined with internally contracted multi-state complete active space second-order perturbations theory (XMS-CASPT2) and guarantees invariance of the theory with respect to unitary rotations of the reference functions.
Explicitly correlated multireference configuration interaction: MRCI-F12.
An internally contracted multireference configuration interaction is developed which employs wave functions that explicitly depend on the electron-electron distance (MRCI-F12). This MRCI-F12 method
BAGEL: Brilliantly Advanced General Electronic‐structure Library
TLDR
The capabilities of the Brilliantly Advanced General Electronic‐structure Library (BAGEL) program package are reviewed, which includes analytical CASPT2 nuclear energy gradients and derivative couplings, relativistic multireference wave functions based on the Dirac equation, and implementations of novel electronic structure theories.
On-the-Fly CASPT2 Surface-Hopping Dynamics.
  • J. Park, T. Shiozaki
  • Computer Science, Physics
    Journal of chemical theory and computation
  • 1 June 2017
We report the development of programs for on-the-fly surface-hopping dynamics simulations in the gas and condensed phases on the potential energy surfaces computed by multistate multireference
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