History
The QUANTICS package solves the time-dependent Schroedinger equation to simulate nuclear motion by propagating wavepackets. Various algorithms are possible, depending on the system of interest and the accuracy required. The focus of the package is the Multi-Configurational Time-Dependent Hartree (MCTDH) algorithm. The package grew out of the Heidelberg MCTDH Package. A brief history is written in Comp. Phys. Comm. (2020) 248: 107040
Capabilities
- Grid-based Wavepacket Propagation
- standard MCTDH
- multi-layer MCTDH (ML-MCTDH)
- MCTDH including Gaussian Basis Functions (G-MCTDH)
- Numerically exact (standard)
- Numerically exact using real WP propagation
- Gaussian Wavepacket Propagation using vMCG algorithm
- Direct dynamics using DD-vMCG
- Classical trajectories and Trajectory Surface Hopping
- Direct dynamics using DD-TSH
- Control calculations using either OCT or LCT.
- Eigenvalues and eigenfunctions
- Energy Relaxation to obtain the ground eigenstate
- Improved Relaxation to obtain eigenstates and eigenenergies of ground and/or low lying excited states.
- Direct diagonalisation of a Hamiltonian matrix using Lanczos
- Filter Diagonalisation to find the eigenvalues of a system from a wavepacket propagation.
- Density Matrix propagation for open or closed systems
- Potential energy function fitting to the MCTDH product form using the natural potential algorithm.
- Fitting a vibronic coupling model Hamiltonian.
In general, the input is made using ascii files. This enables a system to be set up with the minimum of effort. In particular, simple model system can be studied without any need to program. Options available include
- A wide range of DVRs to suit most situations, including 2D-DVRs/FBRs for the treatment of coupled theta/phi degrees of freedom.
- Operators may contain time-dependent terms, i.e. include a laser field.
- CAPs may be used to maintain the boundary conditions, and for the analysis of a system evolution.
- Propagation may be made on a cut through a potential function using a "point DVR".
Special features of the MCTDH wavepacket propagation are that:
- Non-adiabatic systems can be handled using the single- or multi-set formalismus.
- The CDVR method can be used for the evaluation of any multi-dimensional integrals
New Features
Version 2.1
Updates and improvements throughout the code have been made.
New features:
- Direct Dynamics uses an SQL database rather than flat files.
Various features from the Heidelberg
MCTDH Packages have been added including:
- Dynamic Expansion of an MCTDH wavefunction (David Tpia-Mendive)
- Integration schemes avoiding regularisation of the
density matrix (Hans-Dieter Meyer)
Version 2.0
Updates and improvements throughout the code have been made.
New features:
- Thermal Relaxation for Density Matrices (Alice vanHaeften)
Various features from the Heidelberg
MCTDH Packages have been added including:
- ML-Potfit (Frank Otto)
- MC-Potfit (Markus Schroeder)
Version 1.3
Updates and improvements throughout the code have been made.
- Improvements and additions to VCHam (Sandra Gomez)
- Improvements to vMCG integration stability
(Graham Worth, Georgia Christopoulou)
- Improvements to rhoMCTDH (Graham Worth, Ceridwen Ash)
New features to the propagation:
- Exact dynamics with density matrices (Ceridwen Ash)
New features to the Direct Dynamics code:
- Revised Shepard Interpolation (Georgia Christopoulou)
- Local Databases (Georgia Christopoulou)
- MPI for DD-vMCG and interface to QC programs (Thierry Tran)
- Point group symmetry can be used when generating a DD DB
(Antonia Freibert).
New analysis programs:
- Trafodb (Antonia Freibert)
- Cleandb (Graham Worth)
- Rdcheck now runs with keywords to extend usage (Graham Worth)
To be noted:
- For DD-vMCG calculations the refdb.dat file is
now automatically generated and there is no longre a need for it
to be included in an empty database
Version 1.2
Updates and improvements throughout the code have been made.
- Thermal Relaxation for Density Matrices (Alice vanHaeften)
- ML-Potfit (Frank Otto)
- MC-Potfit (Markus Schroeder)
Version 1.3
Updates and improvements throughout the code have been made.
- Improvements and additions to VCHam (Sandra Gomez)
- Improvements to vMCG integration stability
(Graham Worth, Georgia Christopoulou)
- Improvements to rhoMCTDH (Graham Worth, Ceridwen Ash)
New features to the propagation:
- Exact dynamics with density matrices (Ceridwen Ash)
New features to the Direct Dynamics code:
- Revised Shepard Interpolation (Georgia Christopoulou)
- Local Databases (Georgia Christopoulou)
- MPI for DD-vMCG and interface to QC programs (Thierry Tran)
- Point group symmetry can be used when generating a DD DB
(Antonia Freibert).
New analysis programs:
- Trafodb (Antonia Freibert)
- Cleandb (Graham Worth)
- Rdcheck now runs with keywords to extend usage (Graham Worth)
To be noted:
- For DD-vMCG calculations the refdb.dat file is
now automatically generated and there is no longre a need for it
to be included in an empty database
Version 1.2
Updates and improvements throughout the code have been made.
New features to the propagation:
- Chebyschev, SOD and SPO integrators for exact dynamics (Eryn Spinlove, Marcus Taylor, Ceridwen Ash)
- Lobatto DVR (Eryn Spinlove)
- Direct Diagonalisation (Graham Worth)
- Thermal relaxation for density matrices (Graham Worth)
- rhoGMCTDH implemented (Graham Worth)
- ML-rhoMCTDH implemented (Graham Worth)
- GAP-vMCG implemented (Gareth Richings and Iakov Polyak)
- Use of continuum electronic basis changed (Graham Worth)
- Interface to QC program QChem (Johannes Ehrmeier)
- Interface to QC program Molcas (Angelo Giussani, Morgane Vacher)
- Interface to the Zagreb Surface Hopping code (Cristina Sanz Sanz, Johannes Ehrmeier)
Version 1.0 - 1.1
QUANTICS has many new features compared to the older MCTDH packages. The main changes are the addition of the G-MCTDH algorithm and the direct dynamics DD-vMCG method. It also has an implementation of the real wavepacket propagation algorithm for scattering. The code is now Fortran 90 based with full dynamical allocation of memory. Parallelisation using OpenMP and MPI is made in many parts of the code. The file structures have been updated to use tagging to make reading the information easier if new data is added. To be noted, in particular by Heidelberg MCTDH users,
- Version numbers are no longer appended to executable names.
- The potential routines are in a dynamic library and there is no need to compile a potential routine manually before running a calculation. User potentials can also be added via a dynamic library with no need to recompile the code.
- Automatic spline fits of data to provide potential functions.
- Showsys can plot the potential directly from the oper file.
- Rdcheck program changed to use arguments to control data to be read from check file.
- Hessian updating for DD-vMCG (Iakov Polyak)
- Grid-based direct dynamics (DD-GB) (Gareth Richings)
- Gaussian Processing fitting of potential surfaces (Gareth Richings, Iakov Polyak)