  We show a strong mesoscopic transverse growth arrest that co-exists with a
high-speed longitudinal growth in single-crystalline KDP crystals with large
aspect ratios. To explain this unique growth morphology, which cannot be
explained by any current theories, we introduce a new set of surface
concentration rate equations and demonstrate a molecular-orientation-selective
surface self-shielding and channeling mechanism. We introduce a local
supersaturation and calculate crystal growth driving force and growth rate,
demonstrating quick arrest of both quantities as results of
molecule-orientation selectivity based self-shielding and channeling effects.
The growth dynamics thus derived can satisfactorily explain all experimental
observations in single-crystalline KDP crystal growth reported here.
