Electronic correlations influence on the anomalous constitutive law between the structure and spectra of hydrogen bonds

Abstract

Classical constitutive law between the structure and spectra has long been established in most physical processes and behaviors. Despite the emerging consensus, whether this law applies to microscopic systems adhering to quantum mechanics remains a fundamental and open question, due to limitations in even the most state-of-the-art experimental techniques. Here, we report an anomalous constitutive law of hydrogen bonds (X-H···Y) using a benchmark method. Notably, a donor X-H bond shortening occurred simultaneously with an unexpected redshift and enhanced intensity in IR spectra. The reason for donor X-H bond shortening is attributed to both the slowly increasing attractive force from the acceptor Y atom and the increasing short-range repulsive forces from other protons attached to the approaching acceptor Y atom. Furthermore, neither eliminating vibrational mixing nor introducing various physical effects make vibrational spectra respond to X-H bond shortening. Other structural-characterization NMR spectra provide robust evidence for this anomalous law. This anomalous law is ascribed to the interplay of electronic correlations. Our Letter thus inspires a reassessment of paradigms, which broadens the scope of microscopic behavior for finer control. Published by the American Physical Society 2024