Strong electron correlation can be captured with multireference wave function methods, but an accurate description of the electronic structure requires accounting for the dynamic correlation, which they miss. In this work, a new approach for the correlation energy based on the adiabatic connection (AC) is proposed. The AC n method accounts for terms up to order n in the coupling constant, and it is size-consistent and free from instabilities. It employs the multireference random phase approximation and the Cholesky decomposition technique, leading to a computational cost growing with the fifth power of the system size. Because of the dependence on only one- and two-electron reduced density matrices, AC n is more efficient than existing ab initio multireference dynamic correlation methods. AC n affords excellent results for singlet–triplet gaps of challenging organic biradicals. The development presented in this work opens new perspectives for accurate calculations of systems with dozens of strongly correlated electrons.

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The optical function of acrylic cylinders used in keratoprostheses is demonstrated by using a water-filled minicamera as a model of the aphakic human eye. Lengths and diameters of the optical cylinders are important factors influencing the visual fields. The dimensions to be chosen, depends on the thickness of the cornea and the supporting tissues. The most suitable combination of visual field, magnification and diameter of the retinal image field is obtained with optical cylinders with a concave posterior surface. Using a fixed radius of curvature of the posterior surface, the radius of the anterior surfaces are calculated to make the eye emmetropic. With such a cylinder of length 4.5 mm and diameter 2.1 mm a circular visual field of 48" is obtained. With cylinder length 6.0 mm the visual field is at least 35'. The retinal image is about 190/0 larger than that of the normal phakic eye. Cylinder length exceeding 6.0 mm require a greater diameter to provide an adequate visual field. With cylinder lengths up to (3.0 mm and diameters not less than 2.1 mm, the diameter of the retinal image field is at least 12.0 mm. Accidental obliquity of the optical cylinder or off-center implantation give the possibility of undesired projection of the image field outside the macula. The obliquity or degree of off-center implantation tolerance is calculated. The retinal image may be improved by darkening the side of the cylinder.

Breaking the spatial symmetry in optical systems has become a key approach to the study of nonlinear dynamics, wave chaos, and non-Hermitian physics. Moreover, it enables tailoring of the spatiotemporal properties of such systems. Breaking the circular symmetry of lasers yields a more uniform light intensity profile within the optical aperture and makes uniform the spectral distribution of the optical states (modes). Those effects are known to enhance spontaneous as well as stimulated emission and consequently suppress undesired nonradiative recombination in the active region, but their importance for laser emission is not fully understood so far. In this paper, using the example of vertical-cavity surface-emitting lasers, we show that intentionally deformed optical apertures induce a more uniform light intensity distribution within the optical aperture, related to wave chaos, and a higher density of optical states, enhancing stimulated emission as predicted by quantum electrodynamics theory. These two phenomena contribute to increasing the optical output power by more than 60% and quantum efficiency by more than 10%. The results of this study are of significant importance for a variety of lasers, showing a clear link between the fundamentals of their operation and quantum electrodynamics and providing a general, robust method of enhancing emitted power for high-power broad-area lasers.