electronic correlations, may well be consistent with the data.

Zn as phase impurity
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![(Color online) LDOS of a phase impurity with $\alpha=1.5$ as a function of the change in the local gap $\delta \Delta$ within the $5\times
5$ patch in which it lies. The red curve is similar to the results in Ref. , which reported the LDOS near a phase impurity in a homogeneous superconductor. The inset shows the LDOS without the phase impurity (same color code).[]{data-label="fig7"}](phase_impurity_figure.eps){width="1.\columnwidth"}

One of the more exotic proposals to describe the LDOS measurements near Zn impurities is the so-called phase impurity scenario.[@andersen05] As was shown in Ref. , local sign changes of the pairing amplitude on the four nearest bonds to the impurity site can generate low-energy Andreev resonant states with the correct real-space distribution (without a filter mechanism). This is true only for a sufficiently small conventional impurity potential (see Ref. for details).[@andersen05] Using the same notation as in Ref. , we introduce the parameter $\alpha$ which sets the strength of the phase impurity by adding a potential in the $\tau_1$ Nambu channel of $V_1=-\alpha \Delta_0$ which affects only the four NN bonds to the impurity site in the center of the 