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v3.2.2
Abstract:
What makes atoms stick together in molecules and solids, exactly? To answer that, population analysis as imagined by Mulliken (1955) has held a prominent place in quantum chemistry for decades already. Likewise, periodic bonding indicators such as COOP (introduced in 1983) and its density-functional theory equivalent COHP (from 1993) have been helpful, the latter carried out using local-basis codes such as LMTO. Such analysis has allowed to chemically understand three-dimensional Peierls distortions, spin polarization in itinerant magnets, stochiometries of phase-change materials, and a lot more. While plane-wave packages such as VASP, ABINIT, Quantum ESPRESSO etc. offer computational advantages, they lack locality, so the aforementioned chemical concepts were unavailable. Nonetheless, all local bonding information can be analytically reconstructed by transferring plane-wave pseudopotential data to local auxiliary bases built from contracted Slater-type orbitals, as implemented in the LOBSTER (Local-Orbital Basis Suite Towards Electronic-Structure Reconstruction) code, freely available at www.cohp.de, and it also offers other tools like the density-of-energy, crystal-orbital bond index, as well as established quantum-chemical descriptors such as Mulliken or Löwdin charges. All that will be illustrated, using essentially non-mathematical reasoning, from a variety of recent chemical examples.