What Does PNO Stand For?

PNO stands for Pair Natural Orbital

PNO, or Pair Natural Orbital, is a theoretical concept in quantum chemistry that describes a mathematical representation of electron pairs in a many-electron system. It optimizes the description of electron correlation by expressing the electronic wave function in terms of pairs of natural orbitals, enhancing the accuracy of calculations in molecular systems. PNO methods are particularly useful in computational approaches for determining the electronic structure and properties of complex molecules.