The coupled-cluster (CC) equations are most frequently solved via fixed-point (FP) iterations. However, when formulated in a non-canonical gauge, as in local correlation CC, the FP iteration may converge slowly or even diverge. Practical fixes, such as level-shifting and a direct inversion of iterative subspace (DIIS), often improve the convergence, but remain fundamentally heuristic and gauge dependent. {\it Yang et al.}~demonstrated that preconditioned Newton--Krylov (PNK) methods provide substantial wall-time advantage for canonical CC. In this work, we generalize the preconditioner to arbitrary gauges by replacing the energy denominator with a gauge-invariant formulation. Combined with Krylov-based approximate Jacobian inversion, the resulting framework removes the need for level-shifting and yields robust and efficient convergence across various gauges and challenging chemical systems. Our numerical results indicate that PNK consistently outperforms carefully optimized FP-based approaches across a range of molecular systems, positioning the proposed PNK method as a promising new standard for solving the CC equations.
Diffusion quantum Monte Carlo (DMC) and coupled cluster theory [CCSD(T)] are widely used benchmark methods for noncovalent interactions (NCIs). However, recent studies have reported notable discrepancies for several hydrogen-bonded and dispersion-dominated systems, raising questions about the accuracy of the approximat...
Kousuke Nakano, B. X. Shi, D. Alfé et al.· Journal of Chemical Physics· 1 citation
State-of-the-art solvers for the Dirac equation in Lattice QCD are based on adaptive multigrid methods. These require fine-tuning of many algorithmic parameters to achieve optimal performance. We apply a new multigrid approach to Lattice Field Theory adapted from oil-reservoir simulations: Structured-Multiscale Algebra...
Pauline Schauerte, Jaime Fabi'an Nieto Castellanos, A. Krechel et al.· 0 citations
An energy-optimal generalized scalar auxiliary variable (EOP-GSAV) framework for nonlinear index-one port-Hamiltonian differential-algebraic equations (pH-DAEs) is developed, exploiting the port-Hamiltonian structure to separate the nonlinear effort, interconnection, and dissipation terms from a constant implicit core.
Aashutosh Sharma, Andreas Bartel, Manuel Schaller· 0 citations
In this work, we recast two widely used acceleration methods for fixed-point iterations, Anderson acceleration (AA) and the nonlinear generalized minimal residual method (NGMRES), as two-grid methods. By explicitly deriving the error propagation matrices for AA and NGMRES on linear problems, we show that both methods,...
J. Adler, Yun-Hui He, Xiao-Zhe Hu et al.· 0 citations
Constrained density functional theory (CDFT) provides a powerful framework for describing electronically excited and charge-localized states, which underlie a broad range of physical and chemical phenomena. However, the discretized optimization problems arising from CDFT calculations remain challenging, owing to the pr...
This work introduces a common framework based on the discretization of functional Gauss--Newton problems by finite families of linear measurements and shows that, through an appropriate duality pairing, the linear measurements can be represented by test functions.
Nilo Schwencke, Roland Maier· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
