Ab Initio Studies of Stepped {100} Surfaces of KDP Crystals

摘要

Potassium dihydrogen phosphate (KH_2PO_4,KDP) crystals have important uses in laser components and are grown in large scale for that purpose.The need for habit control has led to interest in the step-pinning mechanisms that cause growth inhibition of the {100} face.Model systems representing five stepped KDP {100} surfaces are prepared and studied using ab initio quantum methods.Results of Hartree-Fock and density functional theory plane-wave calculations are presented,including estimated energies of ion and column removal for the steps.Steps terminated by phosphate ions are found to be less energetically favorable than their potassium-terminated counterparts.In addition,surface layer removal energies for the {100} face and the potassium-bounded and phosphate-bounded {101} faces are reported.The potassium-bounded {101} face is found to have a greater surface removal energy than the unexpressed phosphate-bounded {101} face.