**Environ-0.2 ** is the latest release of Environ. It is interfaced with

the **Quantum-ESPRESSO** package and compatible with

versions QE-5.1.X, QE-5.2.X, QE-5.3.0, and QE-6.X. Some of the new

features of this release are not available in the older distributions

of Quantum-ESPRESSO (see the list below for details).

The new features of Environ-0.2 are the following:

- Fully tested and easier to use external fixed charge densities of arbitrary shape and dimensionality (from QE-5.1.X).
- External user-defined dielectric regions of arbitrary shape and dimensionality, to simulate the effect of complex environment such as interfaces, substrates, nanoparticles, etc. (from QE-5.2.1).
- Preconditioned solvers for the generalised Poisson equation, to provide alternative (possibly faster and more robust) numerical approaches to the continuum dielectric solvation model (from QE-5.1.X).
- Restart, with the possibility to include environment effects from the initialisation step, providing a substantial speedup for geometry optimisation calculations (from QE-5.2.1).

The previous functionalities of Environ, available to all the supported distributions of Quantum-ESPRESSO, are the following:

- Continuum dielectric solvation model, defined self-consistently on the electronic density of the system.
- External pressure model, defined in terms of the quantum-volume of the system.
- External surface tension model, defined in terms of the quantum-surface of the system.
- Point-counter-charge correction schemes to remove periodic boundary conditions artefacts in isolated (0D) and slab (2D) systems.
- Modifications of Martyna-Tuckermann and Makov-Payne PBCs correction schemes to account for the presence of a continuum dielectric embedding.

The above functionalities are coupled with the following types of calculations:

- Possibility to perform single point calculations, geometry optimizations, and Born-Oppenheimer molecular dynamics simulations, through the
**PW code**of the Quantum-ESPRESSO package. - Possibility to perform transition state calculations via the nudged elastic band method, through the
**NEB code**of the Quantum-ESPRESSO package. - Possibility to perform the calculation of optical spectra via time-dependent density functional perturbation theory, through the
**TDDFpT code**(only for the continuum dielectric contribution). - Only starting from QE-5.3.0, Environ-0.2 is coupled with the
**CP code**of the Quantum-ESPRESSO package, to perform Car-Parrinello and damped molecular dynamics simulations.

All the above simulations are compatible with the main features of Quantum-ESPRESSO, namely pseudo-potentials-based plane-wave periodic-boundary-conditions simulations at the density functional theory level, with k-point integration. In particular the following features are all compatible with Environ (a more comprehensive list of the capabilities of Quantum-ESPRESSO can be found in the project documentation):

- Norm-conserving, ultrasoft and projector-augmented wave (PAW) pseudopotentials.
- Local density approximation (LDA) functionals, Generalized Gradient approximation (GGA) functionals, hybrid functionals, van der Waals (vdW) nonlocal density functionals.
- Hubbard U.

The features which are still not available and are under development are:

- User-friendly installation procedure: the set up of the module inside the released Quantum-ESPRESSO package is still not user-friendly and requires to follow a rather simple, but long, procedure.
- Coupling with the GIPAW code of the Quantum-ESPRESSO package, to calculate magnetic resonance spectra.