[Pw_forum] Continuum solvation in Quantum-ESPRESSO: Environ module released

[Oliviero Andreussi]

Dear users of Quantum-ESPRESSO,

In the past years and together with other researchers and developers of 
QE (Nicola Marzari, Ismaila Dabo, Iurii Timrov and others) I have been 
developing a module, interfaced with PW and other programs of the QE 
distribution, aimed at describing the effects of external environments, 
treated as classical continuum bodies, on first-principles systems. This 
email is to advertise the first public release of this module 
http://qe-forge.org/gf/project/electroemb/frs/, with more information 
available on the project website: www.quantum-environ.org

The main feature of the module, named Environ, is the possibility to 
include in the Hamiltonian of the system the electrostatic effects of a 
continuum dielectric solvent, similarly to what is commonly done in the 
quantum-chemistry literature by approaches such as the Polarizable 
Continuum Model (PCM) or COSMO. Similarly to these methods, the 
continuum approximation allows to introduce environment (solvent) 
effects in a computationally inexpensive way, with the final cost of the 
calculation being only slightly higher than a calculation in vacuum. 
Contrary to those methods, our approach has a natural definition of the 
boundary between the quantum-mechanical and the continuum region, based 
on the work of Fattebert and Gygi (2002, 2003), Scherlis et al (2006) 
and our own (2012, 2013), which adapts self-consistently to the 
electronic density of the system and relies on a much limited number of 
numerical parameters: from this the acronym SCCS, self-consistent 
continuum solvation, that identifies the solvation model at the core of 
Environ.

SCCS is ideally suited for periodic and partially periodic (slab, wires) 
systems (Andreussi 2014) and, being interfaced with PW, allows to treat 
metallic systems and to perform molecular dynamics simulations. In 
addition to PW, also the NEB code, for the calculation of reaction 
paths, and the TDDFpT code, for the calculation of optical spectra, can 
be used with Environ, the latter thanks to the work of Iurii Timrov and 
Stefano Baroni (Timrov 2015). Extensions to interface Environ with the 
CP code are in progress.

A few applications of the module have already appeared in the 
literature, a full bibliography is available on the website homepage. 
Basic instructions on installation of the module and on performing 
simulations with it are also available in the documentation section of 
the webpage http://www.quantum-environment.org/documentation.html and I 
would be more than happy to clarify any doubt and provide support, in 
case those information were insufficient.

Best regards,

Oliviero Andreussi

Senior Postdoctoral Associate
Universita' della Svizzera Italiana
Lugano, Switzerland

References:
J. L. Fattebert and F. Gygi, J. Comput. Chem. 23, 662 (2002).
J. L. Fattebert and F. Gygi, Int. J. Quantum Chem. 93, 139 (2003).
D. A. Scherlis, J. L. Fattebert, F. Gygi, M. Cococcioni, and N. Marzari, 
J. Chem. Phys. 124, 074103 (2006).
O. Andreussi, I. Dabo, and N. Marzari, J. Chem. Phys. 136, 064102 (2012).
C. Dupont, O. Andreussi, and N. Marzari, J. Chem. Phys. 139, 214110 (2013).
O. Andreussi and N. Marzari, Phys. Rev. B 90, 245101 (2014).
I. Timrov, O. Andreussi, A. Biancardi, N. Marzari and S. Baroni, J. 
Chem. Phys. 142, 034111 (2015).