When evaluating an integral on a grid, the finite resolution thereof can affect the accuracy of the result. In the context of atomistic simulation, this is because a slight change in nuclear coordinates will affect the mapping on the grid. For smooth properties like the electron density, there is a […]
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Hard drives are slow. It does not matter whether we are talking HDD or SDD drives, it matters what we compare it to. In the context of high-performance computing, this means memory (RAM). To set this into perspective, here are some common approximate timings alongside a more intuitive “human scale” […]
The electron density of a molecule is very far from an equally distributed charge density. Therefore, the common density sampling on a regular grid for visualisation purposes is not useful for cases where numerical properties of the density distribution are sought after. In that case, integration grids as Becke-Lebedev grids […]
Many people in Switzerland commute and most of them use SBB to do so. The only catch: SBB has no interest in being fast: “Not as fast as possible, but as fast as necessary.” This means that for a typical commuter between Zurich and Basel, SBB thinks it is acceptable […]
Duplicating the whole TeX distribution on both Windows and Windows Subsystem for Linux (WSL) is not only a waste of disk space, it is also a maintainability nightmare. Now to build LaTeX documents from Sublime Text 3 as Windows application is quite easy if you have WSL with texlive up […]
When running a transition state search or geometry optimisation in orca, some of the quantites like forces in cartesian coordinates are only written to the *.opt file that is not mentioned in the manual. Here is a description of the file contents and formats. The file is set up in […]
This post describes how to run the quantum chemical software package orca on particular clusters. The problem Orca’s parallel implementation relies on a particular OpenMPI version (2.0.2) which is called via a system call to mpirun. Now some clusters do not support mpirun, as they run in SLURM native mode. […]