29 research outputs found
A Doubly Nudged Elastic Band Method for Finding Transition States
A modification of the nudged elastic band (NEB) method is presented that
enables stable optimisations to be run using both the limited-memory
quasi-Newton (L-BFGS) and slow-response quenched velocity Verlet (SQVV)
minimisers. The performance of this new `doubly nudged' DNEB method is analysed
in conjunction with both minimisers and compared with previous NEB
formulations. We find that the fastest DNEB approach (DNEB/L-BFGS) can be
quicker by up to two orders of magnitude. Applications to permutational
rearrangements of the seven-atom Lennard-Jones cluster (LJ7) and highly
cooperative rearrangements of LJ38 and LJ75 are presented. We also outline an
updated algorithm for constructing complicated multi-step pathways using
successive DNEB runs.Comment: 13 pages, 8 figures, 2 table
A Simple Affine-Invariant Spline Interpolation over Triangular Meshes
Given a triangular mesh, we obtain an orthogonality-free analogue of the classical local Zlámal–Ženišek spline procedure with simple explicit affine-invariant formulas in terms of the normalized barycentric coordinates of the mesh triangles. Our input involves first-order data at mesh points, and instead of adjusting normal derivatives at the side middle points, we constructed the elementary splines by adjusting the Fréchet derivatives at three given directions along the edges with the result of bivariate polynomials of degree five. By replacing the real line R with a generic field K, our results admit a natural interpretation with possible independent interest, and the proofs are short enough for graduate courses