水的核量子效应研究进展

Recent advances in nuclear quantum effects of water

水之所以如此复杂,主要是源于水分子之间的氢键相互作用。人们通常认为氢键的本质为经典的静电相互作用,然而由于氢原子核是质量最小的原子核,其量子特性(量子隧穿和量子涨落)往往不可忽视,它们直接影响着氢键体系的结构与物性。如何实现对核量子效应的精准探测和描述是一个科学难题。本研究团队经过多年的努力,成功发展了一套对原子核量子态敏感的扫描隧道显微术和高效的全量子化计算方法,首次获得水分子的亚分子级成像并观察到氢核的协同量子隧穿,在国际上率先测定了氢键的量子成分,提出了"核量子涨落弱化弱氢键、强化强氢键"的物理图像。这些奠基性的研究成果澄清了核量子效应领域长期争论的关键问题,并引领了该方向的发展。

The mystery of water mainly arises from the intermolecular hydrogen-bonding interaction.It is well known that hydrogen bonds have a strong classic component coming from electrostatics.However,its quantum component can be exceptionally prominent due to the quantum tunneling and zero-point motion of light hydrogen nuclei（proton）,which play important roles in the structure,dynamics,and macroscopic properties of hydrogen-bonded materials.However,accurate and quantitative description of nuclear quantum effects have proven a great challenge for decades.After enormous efforts in the last few years,we have developed a series of experimental techniques based on the scanning probe microscopy,which allow us to access the quantum degree of freedom of protons both in real and energy space.Theoretically,we have implemented highly efficient path-integral molecular dynamics calculation methods,in which both electrons and nuclei are treated as quantum particles.Those novel techniques and methods enable us to directly visualize the concerted quantum tunneling of protons within the hydrogen-bonded network and quantify the quantum component of a single hydrogen bond at a water-solid interface for the first time.Furthermore,we unravel a general physical picture for the nuclear quantum effects of hydrogen bonds,that is,the anharmonic quantum fluctuations of hydrogen nuclei weaken the weak hydrogen bonds and strengthen the strong ones.These pioneering findings clarify the long-standing puzzles in nuclear quantum effects of water and enable us to lead this research field in the world.