Welcome to the simsem and semTools forum! simsem and semTools are R packages (available on CRAN) that provide additional functionality for structural equation modeling in R.
simsem provides comprehensive simulation functionality for structural equation modeling. simsem allows data generation based on a user specified model, analyses of generated data, and storage and processing of simulation results. Data generation and analysis models using can be specified using lavaan syntax, or OpenMx model specifications, or a set of matrices.
For further details on simsem see: http://simsem.org
semTools is a package comprised of useful functions for structural equation modeling in R. semTools is designed to be a user supported package and all users of SEM and R are encouraged to submit functions of ideas for additional functions. semTools includes the functions, fitMeasuresMx, nullMx, and saturateMx, which compute fit measures, a null model and a saturated model with OpenMx.
For more information on semTools see: https://github.com/simsem/semTools/wiki