Stochastic search for isomers on a quantum mechanical surface.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Identifying stable molecular isomers is crucial for understanding chemical bonding and reactivity.
• Exploring the potential energy surface of molecules helps predict their properties and structures.
• Carbon clusters, like C6, exhibit diverse bonding motifs and structures.

Purpose of the Study:

• To develop and apply a stochastic search procedure for locating all energy minima (isomers) on a molecular potential energy surface.
• To identify novel singlet structures of the C6 carbon cluster using quantum mechanical calculations.
• To explore the applicability of this search method for identifying transition states.

Main Methods:

• Utilized a stochastic search procedure involving random kicks followed by geometry optimization.
• Employed quantum mechanical calculations with the restricted Hartree-Fock (RHF) method and the 6-311G basis set.
• Systematically searched for singlet isomers of the C6 carbon cluster.

Main Results:

• Successfully located 11 new, previously undiscovered singlet isomers of the C6 carbon cluster.
• These newly found structures, in addition to known linear and ring forms, expand the known isomer landscape for C6.
• The identified structures offer insights into diverse qualitative bonding motifs within this carbon cluster.

Conclusions:

• The stochastic search method is effective for comprehensively identifying molecular isomers.
• The study expands the known structural diversity of the C6 carbon cluster.
• The methodology shows promise for locating transition states in chemical reactions.