Double hybrid approximate functionals have "unoccupied" Kohn-Sham orbitals in their formulations due to their MP2 component; however, the "exact functional" depends only on the "occupied" K-S orbitals. Thus the only way double hybrid approximations could approximate the "exact" functional is that...

High–quality protein backbone reconstruction from alpha carbons using Gaussian mixture models The above research paper is about a software tool for reconstructing a protein's main chain model only from its alpha-carbon backbone (aka, C-alpha trace). This tool provides two options: conversion (1...