NBO 7.0: New vistas in localized and delocalized chemical bonding theory

We briefly outline some leading features of the newest version, NBO 7.0 , of the natural bond orbital (NBO) wavefunction analysis program. Major extensions include: (1) a new NPEPA module implementing Karafiloglou's “polyelectron population analysis” in the NBO framework; (2) new RDM2 program infrastructure for describing electron correlation effects based on full evaluation of the second‐order reduced density matrix; (3) improved convex‐solver implementation of natural resonance theory (NRT), allowing a greatly expanded range of applications and associated “resonance NBO” (RNBO) visualization of chemical reactivity; (4) a variety of other improvements in well‐established NBO algorithms. We also provide brief introduction to the new NBOPro@Jmol utility program, a plugin to the Jmol chemical structure viewer that serves as a convenient tool to provide on‐demand NBO descriptors or orbital visualizations for a broad variety of chemical inquiries in research or classroom applications. © 2019 Wiley Periodicals, Inc.