Density functional theory study on (LiNH2)n (n=1-5) clusters.

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Understanding the properties of small atomic and molecular clusters is crucial for developing new materials and chemical processes.
• Lithium amide clusters are of interest due to their potential applications and unique bonding characteristics.

Purpose of the Study:

• To investigate the geometrical structures and relative stabilities of lithium amide ((LiNH(2))(n), n=1-5) clusters.
• To analyze the electronic, vibrational, and thermodynamic properties, including N-H bond dissociation energies (BDE) and ionization potentials.

Main Methods:

• Density Functional Theory (DFT) calculations were performed using B3LYP/6-31G* and B3LYP/6-31++G* levels.
• Analysis included electronic structures, vibrational frequencies, N-H bond dissociation energies (BDE), thermodynamic properties, and Natural Bond Orbital (NBO) analysis.

Main Results:

• Li-N and Li-Li bonds are more favorable than Li-H or N-H bonds in these clusters.
• Average binding energies per LiNH(2) unit increase with cluster size (n), and Natural Bond Orbital (NBO) analysis indicates strong ionicity in Li-NH(2) bonds.
• Ring-like clusters ((LiNH(2))(3,4)) exhibit higher stability, ionization energy, and band gap, with lower HOMO energy compared to other structures.

Conclusions:

• The study reveals that Li-N bonding is dominant, with strong ionic character, and identifies stable ring-like structures for lithium amide clusters.
• Thermodynamic analysis suggests facile cluster formation at low temperatures, with a tendency towards more complex ring structures.
• The N-H bonds in singlet clusters are stable, while those in triplet clusters are prone to dissociation, and cluster properties resemble those of crystalline lithium amide.