VOLUME57, NUMBER22 P H Y S I C A L R E V I E W L E T T E R S 1 DECEMBER 1986

ERRATA

Theory of Electron Band Tails and the Urbach Optical-Absorption Edge. SAJEEV JOHN, COSTAS SOUKOULIS, MORREL H. COHEN, and E. N. ECONOMOU [Phys. Rev. Lett. 57, 1777 (1986)].

There is a typographical omission in Eq. (7b). It should read

ea = ftV2ma2-4|£|/(4~rf)(n-U + [ 4 / ( 4 - d ) P | £ | / e J i / 2 j " ^

The exponent of -j acting on the braces was omitted in the version that appeared in print.

Complexity and the Relaxation of Hierarchical Struc­tures. CONSTANTIN P. BACHAS and B. A. HUBERMAN [Phys. Rev. Lett. 57, 1965 (1986)].

Reference 3 also should have contained the following: G. Paladin, M. Mezard, and C. de Dominicis, J. Phys. (Paris), Lett. 46, L985 (1985).

Quantum Chaos and Statistical Properties of Energy Lev­els: Numerical Study of the Hydrogen Atom in a Mag­netic Field. D. DELANDE and J. C. GAY [Phys. Rev. Lett. 57, 2006 (1986)].

On p. 2009, the caption to Fig. 4 should read, "FIG. 4. A3 statistic of the spectrum (spectral rigidity), (a) Real physical problem (hydrogen in a magnetic field) in the regular regime. The solid line is the Poisson prediction. (b) Oscillator system in the chaotic regime. The solid line is the GOE prediction."

First-Principles Theoretical Explanation of Incommensu­rate Behavior in RbiZnCU. V. KATKANANT, P. J. EDWARDSON, J. R. HARDY, and L. L. BOYER [Phys. Rev. Lett. 57, 2033 (1986)].

Figures 2(a) and 2(b) of this paper have been inadver­tently interchanged; thus, the caption for Fig. 2(a) re­lates to Fig. 2(b) and the caption for Fig. 2(b) relates to Fig. 2(a).

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