# Dimer-Monomer Ground State for Extended Spin-1/2 Diamond Chain

## TL;DR

This paper identifies specific conditions under which the dimer-monomer state is exactly the ground state of an extended spin-1/2 diamond chain, including complex interactions and distortions, using a complete square Hamiltonian approach.

## Contribution

It provides a new exact ground state condition for an extended diamond chain with complex interactions, even without space-reflection symmetry.

## Key findings

- Dimer-monomer state is the ground state under certain conditions.
- Method uses Hamiltonian in a complete square form.
- Applicable to chains with next-nearest-neighbor interactions and distortions.

## Abstract

We present a condition in which the dimer-monomer state is exactly the ground state of an extended diamond chain with spin magnitude 1/2. The Hamiltonian of the extended diamond chain includes next-nearest-neighbor exchange interactions and distortions, where the spin magnitude of the spin pair on a singlet dimer is not generally conserved. The method of deriving the condition is based on representing the Hamiltonian in a complete square form. The dimer-monomer ground state is found even if the Hamiltonian has no space-reflection symmetries.