News: a visualisation package for molecular surfaces is now freely available under the LGPL licence.
ddCOSMO and ddPCM are a recently proposed algorithms to solve the polarization equation for the Conductor-like Screening Model (COSMO) and more generally the Polarisable Continuum Model (PCM), popular Continuum Solvation Models. Traditional implementations of Continuum Solvation Models, including COSMO and the PCM, are based on a Boundary Element Method (BEM) discretization of the associated integral equation and require the solution of a large, dense linear system of equations: while fast summation techniques such as the Fast Multipole Method can be used in iterative solvers, the computational task can easily be quite formidable for large systems. Furthermore, the most recent discretizations are controlled by a large number of parameters and are therefore difficult to control.
ddCOSMO introduces a completely different paradigm, by using domain decomposition to recast the COSMO problem as a collection of local problems which only interact with close neighbors. The result is a large, but very sparse linear system of equations and a very simple discretization setting, as the overall discretization is completely defined by just three parameters: the degree of spherical harmonics that are used, the number of integration points on a sphere and the tolerance for solving the linear system. The scheme is systematically improvable in the sense that refining any the three parameters yields a more accurate approximation. Linear scaling is achieved independent of the shape of the molecule - i.e., even for very globular molecules - and the overall computation has a very reduced cost. With respect to existing linear-scaling implementations, ddCOSMO can be two to three orders of magnitude faster, allowing to compute the solvation energy for very large systems with a reduced computational cost.
ddPCM is a generalization of the domain decomposition paradigm to the PCM that is compatible with ddCOSMO in the sense that the two solutions coincide for very large dielectric permittivities of the solvent.
In this page, you will find some information on the ddCOSMO/ddPCM team, on its development story and a list of references.
A modular implementation of ddCOSMO and instructions on how to interface it to you favorite code can also be downloaded. We distribute the code freely to individuals for non commercial use, but require them to agree to a personal license agreement. An efficient and integrated implementation will also be released within a future Gaussian version and in the Tinker-HP package that will soon be released.