# Understanding the Existence of a Na2 Dimer in a High-Spin State

## TL;DR

Scientists found a high-spin sodium dimer on liquid helium droplets and used advanced calculations to understand its stability and structure.

## Contribution

The study reveals the bonding mechanism and stability of a high-spin Na2 dimer using various computational methods.

## Key findings

- The high-spin Na2 dimer is stabilized by van der Waals interactions with binding energies between -0.030 eV and -0.192 eV.
- The bond length of the dimer ranges from 4.231 Å to 5.108 Å depending on the computational method.
- The experimental setup can help study metastable high-spin clusters like Li4 with magnetic properties.

## Abstract

The recent observation of a high-spin Na2 dimer
formed
on the surface of liquid helium nanodroplets raises some fundamental
questions, as the ground state of Na2 is known to have
zero spin. Is it protected against spontaneous dissociation? What
is its binding energy and interatomic distance? Is it stable at a
higher temperature? Using calculations based on density functional
theory (with and without long-range interaction) and coupled cluster
methods, CCSD­(T), we show that the bonding in the high-spin Na2 dimer is governed by van der Waals interaction with binding
energy (bond length) varying between −0.030 eV (5.108 Å)
and −0.192 eV (4.231 Å), depending on the computational
method used. Thus, the experimental method used by Kresin and co-workers
can be very useful to study larger metastable high-spin clusters such
as Li4 which was predicted in 1985 to have a tetrahedral
structure carrying a magnetic moment of 2 μB, while
its ground state is planar and nonmagnetic.