An electrostatic surface trap for cold polar molecules with three charged poles is proposed. Distance between trap center and chip surface can be manipulated conveniently by altering voltages applied to the poles. Dynamic process of loading and trapping is simulated with classic method of Monte Carlo. It indicates that a loading efficiency of 40% for ND₃ molecular beam with middle velocity of 11 m·s^-1 is reached. Corresponding temperature of trapped molecules is about 25 mK. Our scheme can be further miniaturized and integrated to form one-dimensional and two-dimensional microtrap arrays which can be used in quantum computing and low-dimensional physics research.

With molecular dynamics study,we investigate microstructure of liquid Al₂O₃ at 2663 K and 2223 K.The first and second nearest-neighbor distances are in good agreement with results of Ansell et al.Analysis on coordination numbers and angle-distribution functions show that the microstructure of liquid aluminum oxide mostly consists of three-fold coordination of oxygen,four-fold and five-fold coordination of aluminum.Evidence of liquid-liquid phase transition due to separation of high and low coordinate species is not found.