Related Experiment Video
Updated: Aug 16, 2026

Generation and Coherent Control of Pulsed Quantum Frequency Combs
Published on: June 8, 2018
Nonorthogonal density-matrix perturbation theory
Anders M N Niklasson1, Valéry Weber, Matt Challacombe
1Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. amn@lanl.gov
Abstract:
Recursive density-matrix perturbation theory [A.M.N. Niklasson and M. Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] provides an efficient framework for the linear scaling computation of materials response properties [V. Weber, A.M.N. Niklasson, and M. Challacombe, Phys. Rev. Lett. 92, 193002 (2004)]. In this article, we generalize the density-matrix perturbation theory to include properties computed with a perturbation-dependent nonorthogonal basis. Such properties include analytic derivatives of the energy with respect to nuclear displacement, as well as magnetic response computed with a field-dependent basis. The theory is developed in the context of linear scaling purification methods, which are briefly reviewed.
Related Concept Videos
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
Interference and Diffraction
The Uncertainty Principle
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
Second Uniqueness Theorem
In contrast, consider that the electric field is non-unique and apply Gauss's law in divergence form in the region between the conductors and the integral form to the surface...
Orthogonal Trajectories
