Non-Bloch Dirac Points and Phase Diagram in the Stacked Non-Hermitian SSH Model.

Topological semimetals exhibit protected band crossings in momentum space with

corresponding surface states. Non-Hermitian Hamiltonians introduce geometry-sensitive features

that dissolve this bulk-boundary correspondence principle. In this talk, we exemplify this by

showing a non-Hermitian 2D stacked SSH chain model with non-reciprocal on-site gain/loss. We

obtain an analytical phase diagram of its complex spectrum under open boundary conditions. We

reveal that the model can exhibit non-Bloch Dirac points, which only appears under open

boundary conditions but disappear in Bloch bands under periodic boundary conditions. Due to

the reality of spectrum in the vicinity of non-Bloch Dirac points, we can map it to Hermitian

band crossings within the Altland-Zirnabuer symmetry classes. Based on this mapping, we

demonstrate that non-Bloch Dirac points are characterized by the integer topological charge.

Moreover, the locations of the non-Bloch Dirac points under different boundary geometries do

not match with each other, indicating the breakdown of bulk-boundary correspondence in non-

Hermitian semimetals. Our findings provide new insights into establishing unconventional bulk-

boundary correspondence for non-Bloch Dirac metals in non-Hermitian systems.