An Explicit Lower Bound for the Proportion of Isolated Zeros of the Riemann Zeta Function

We consider the full sequence of nontrivial zeros of the Riemann zeta function with positive ordinate, counted with multiplicity. For every fixed 0 < c <= 10^-5, we prove unconditionally that the lower limiting proportion of zeros whose two neighboring gaps are both strictly larger than 2*pi*c/log X is at least 0.672468. Here X is the common height cutoff, and the neighbors belong to the full zero sequence. This refines Lamzouri's small-fixed-gap lower bound 0.6552... by explicitly implementing a shifted mollified-moment refinement of his approach. The proof combines a shifted mollified second-moment formula with Lamzouri's isolated-zero inequality. A positive shift bounds a truncated first moment of horizontal zero displacements, which is matched to an explicitly certified linear majorant of the projection deficit. We give the horizontal-boundary and global-height arguments, and derive a gap loss 6*pi^2*c^2 uniform over the necessary smoothing. The result is an explicit quantitative refinement using existing analytic inputs; no effective first height is obtained.