  We introduce oxNA, a new model for the simulation of DNA-RNA hybrids which is
based on two previously developed coarse-grained models$\unicode{x2014}$oxDNA
and oxRNA. The model naturally reproduces the physical properties of hybrid
duplexes including their structure, persistence length and force-extension
characteristics. By parameterising the DNA-RNA hydrogen bonding interaction we
fit the model's thermodynamic properties to experimental data using both
average-sequence and sequence-dependent parameters. To demonstrate the model's
applicability we provide three examples of its use$\unicode{x2014}$calculating
the free energy profiles of hybrid strand displacement reactions, studying the
resolution of a short R-loop and simulating RNA-scaffolded wireframe origami.
