PSEUDOMODES FOR BIHARMONIC OPERATORS WITH COMPLEX POTENTIALS.

This article is devoted to the construction of pseudomodes of one-dimensional biharmonic operators with complex-valued potentials via the WKB method. As a by-product, the shape of pseudospectrum near infinity can be described. This is a newly discovered systematic method that goes beyond the standard semiclassical setting which is a direct consequence. This approach can cover a wide class of previously inaccessible potentials, from logarithmic to superexponential ones. [ABSTRACT FROM AUTHOR]