The power of density functional theory is often limited by the high computational demand in solving an eigenvalue problem at each self-consistent-field (SCF) iteration. The method presented in this paper replaces the explicit eigenvalue calculations by an approximation of the wanted invariant subspace, obtained with the help of well-selected Chebyshev polynomial filters. In this approach, only ...

The power of density functional theory is often limited by the high computational demand in solving an eigenvalue problem at each self-consistent-field (SCF) iteration. The method presented in this paper replaces the explicit eigenvalue calculations by an approximation of the wanted invariant subspace, obtained with the help of well-selected Chebyshev polynomial filters. In this approach, only ...

In this paper, we study subspace embedding problem and obtain the following results: 1. We extend the results of approximate matrix multiplication from the Frobenius norm to the spectral norm. Assume matrices A and B both have at most r stable rank and r̃ rank, respectively. Let S be a subspace embedding matrix with l rows which depends on stable rank, then with high probability, we have ‖ASSB−A...

Interpolation polynomial pn at the Chebyshev nodes cosπj/n (0 ≤ j ≤ n) for smooth functions is known to converge fast as n → ∞. The sequence {pn} is constructed recursively and efficiently in O(n log2 n) flops for each pn by using the FFT, where n is increased geometrically, n = 2i (i = 2, 3, . . . ), until an estimated error is within a given tolerance of ε. This sequence {2j}, however, grows ...

We propose a block Davidson-type subspace iteration using Chebyshev polynomial filters for large symmetric/hermitian eigenvalue problem. The method consists of three essential components. The first is an adaptive procedure for constructing efficient block Chebyshev polynomial filters; the second is an inner–outer restart technique inside a Chebyshev–Davidson iteration that reduces the computati...

An infinite dimensional notion of asymptotic structure is considered. This notion is developed in terms of trees and branches on Banach spaces. Every countably infinite countably branching tree T of a certain type on a space X is presumed to have a branch with some property. It is shown that then X can be embedded into a space with an FDD (Ei) so that all normalized sequences in X which are alm...

We extend a result of Ramaré and Rumely, 1996, about the Chebyshev function θ in arithmetic progressions. We find a map ε(x) such that | θ(x; k, l)− x/φ(k) |< xε(x) and ε(x) = O ( 1 lna x ) (∀a > 0), whereas ε(x) is a constant. Now we are able to show that, for x > 1531, | θ(x; 3, l)− x/2 |< 0.262 x lnx and, for x > 151, π(x; 3, l) > x 2 lnx .

We extend a result of Ramaré and Rumely, 1996, about the Chebyshev function θ in arithmetic progressions. We find a map ε(x) such that | θ(x; k, l)− x/φ(k) |< xε(x) and ε(x) = O ( 1 lna x ) (∀a > 0), whereas ε(x) is a constant. Now we are able to show that, for x > 1531, | θ(x; 3, l)− x/2 |< 0.262 x lnx and, for x > 151, π(x; 3, l) > x 2 lnx .

We extend a result of Ramaré & Rumely, 1996 [3] about Chebyshev function θ in arithmetic progressions. We find a map ε(x) such that | θ(x; k, l) − x/φ(k) |< xε(x) and ε(x) = O ( 1 lna x ) (∀a > 0) whereas ε(x) is a constant in [3]. Now we are able to show that | θ(x; 3, l)− x/2 |< 0.262 x lnx and, for x > 151, π(x; 3, l) > x 2 lnx .

Solving the Kohn-Sham eigenvalue problem constitutes the most computationally expensive part in self-consistent density functional theory (DFT) calculations. In a previous paper, we have proposed a nonlinear Chebyshev-filtered subspace iteration method, which avoids computing explicit eigenvectors except at the first self-consistent-field (SCF) iteration. The method may be viewed as an approach...