YetAnotherSimulationSuite.jl (YASS)

A simulation suite for molecular dynamics in Julia.

Calculator

Structure for a calculator object for MD.

Fields

• b: Potential builder.
• e: Energy function.
• f!: Force function.
• ef!: Energy and force function.
• energy_unit: Unitful energy unit
• force_unit: Unitful force unit
• time_unit: Unitful time unit
• constraints: Constraints.

Calculator(b; E=nothing, F=nothing, EF=nothing, constraints=nothing)

Construct a Calculator object.

Arguments

• b: Potential builder.
• E: Energy function (optional).
• F: Force function (optional).
• EF: Energy and force function (optional).
• constraints: Constraints (optional).

Returns

• Calculator object.

Cell{D, B, I, F, S}

Structure representing a simulation cell.

Fields

• lattice: Lattice matrix.
• scaled_pos: Scaled positions.
• velocity: Velocities.
• masses: Masses.
• symbols: Atomic symbols.
• mask: Mask vector.
• PBC: Periodic boundary conditions.
• NC: Neighbor counts.

Cell(lat, spos, vel, mas, sym, mask, PBC, NC)

Construct a Cell object from lattice, positions, velocities, etc.

Arguments

• lat: Lattice matrix.
• spos: Scaled positions.
• vel: Velocities.
• mas: Masses.
• sym: Symbols.
• mask: Mask vector.
• PBC: Periodic boundary conditions.
• NC: Neighbor counts.

Returns

• Cell object.

Dynamics{T,D,B,P,PV,I,F,S}

Structure holding all MD simulation variables.

Fields

• m: Masses.
• s: Symbols.
• mols: Molecule indices.
• temp: Temperatures.
• energy: Energies.
• forces: Forces.
• potVars: Potential variables.
• PBC: Periodic boundary conditions.
• NC: Neighbor counts.
• ensemble: Ensemble object.

HiddenOptVars

Structure for hidden variable optimization.

Fields

• potVars: Potential variables.
• cellBuf: Cell buffer.
• superBuf: Supercell buffer.
• scaleEnergy: Energy scaling factor.
• PBC: Periodic boundary conditions.
• mols: Molecule indices.
• pars: Pair indices.
• T: Transformation matrix.

NVE(cell::MyCell)

Construct an NVE ensemble from a MyCell object.

NVE()

Construct a default NVE ensemble with zero lattice.

NVT{D,T,F}

Structure for NVT (canonical) ensemble.

Fields

• lattice: Lattice matrix.
• thermostat: Thermostat object.

NVT(cell::MyCell, thermostat::MyThermostat)

Construct an NVT ensemble from a MyCell and thermostat.

NVT(thermostat::MyThermostat)

Construct an NVT ensemble with zero lattice and given thermostat.

Particle{D, F, S}

Mutable struct representing an atom in the simulation.

Fields

• r: Position vector.
• v: Velocity vector.
• m: Mass.
• s: Symbol.

Particle(r, v, m, s)

Construct a Particle from position, velocity, mass, and symbol.

Arguments

• r: Position vector.
• v: Velocity vector.
• m: Mass.
• s: Symbol.

Returns

• Particle object.

Traj(imgs, mas, sym, lat)

Construct a Traj object from images, masses, symbols, and lattice.

Arguments

• imgs: Vector of Image objects.
• mas: Vector of masses.
• sym: Vector of symbols.
• lat: Lattice matrix.

Returns

• Traj object.

optVars

Structure holding optimization variables for geometry optimization.

Fields

• potVars: Potential variables.
• mols: Molecule indices.
• m: Masses.
• PBC: Periodic boundary conditions.
• NC: Neighbor counts.
• lattice: Lattice matrix.

vacfInps

Input structure for velocity autocorrelation function (VACF) calculations.

Fields

• vel: Velocity data.
• mas: Masses.
• Hz: Sampling frequency.
• norm: Normalize flag.
• win: Window function.
• pad: Padding factor.
• mir: Mirror flag.

vacfOut

Output structure for VACF and VDOS calculations.

Fields

• c: Raw VACF.
• C: Windowed VACF.
• v: Frequency axis.
• I: Intensity.

deleteat!(cell::MyCell, iter)

Remove atoms at given indices from a cell.

Arguments

• cell: MyCell object.
• iter: Indices to remove.

Side Effects

• Modifies the cell in-place.

getindex(cell::MyCell, inds)

Get cell atoms at inds indicies

Arguments

• cell: MyCell object
• inds: Indices to get

Returns

• Cell object

length(cell::MyCell)

Get number of atoms in cell

Arguments

• cell: MyCell object

Returns

• Number of atoms in cell

length(traj::MyTraj)

Get the number of images in a trajectory.

Arguments

• traj: Traj object.

Returns

• Number of images.

push!(tj::MyTraj, solu::SciMLBase.ODESolution; dt=fs, step=1)

Append images from an ODE solution to a trajectory.

Arguments

• tj: Traj object.
• solu: ODE solution object.
• dt: Time step (default: fs).
• step: Step interval (default: 1).

Side Effects

• Modifies tj in-place.

repeat(cell::MyCell, count::Integer)

Repeat a cell multiple times.

Arguments

• cell: MyCell object.
• count: Number of repetitions.

Returns

• New repeated Cell object.

run(calc, cell, tmax, dt, ensemble; algo=VelocityVerlet(), split=1, kwargs...)

Run an MD simulation for a cell.

Arguments

• calc: Calculator object.
• cell: MyCell object.
• tmax: Time span tuple.
• dt: Time step.
• ensemble: Ensemble object.
• algo: ODE solver algorithm (default: VelocityVerlet()).
• split: Number of segments (default: 1).
• kwargs: Additional keyword arguments.

Returns

• Processed trajectory or solution.

run(calc, cell, tspan, dt, ensemble; algo=VelocityVerlet(), split=1, kwargs...)

Run an MD simulation for a cell.

Arguments

• calc: Calculator object.
• cell: MyCell object.
• tspan: Time span tuple.
• dt: Time step.
• ensemble: Ensemble object.
• algo: ODE solver algorithm (default: VelocityVerlet()).
• split: Number of segments (default: 1).
• kwargs: Additional keyword arguments.

Returns

• Processed trajectory or solution.

run(calc, bdys, tmax, dt, ensemble; algo=VelocityVerlet(), split=1, kwargs...)

Run an MD simulation for a set of atoms.

Arguments

• calc: Calculator object.
• bdys: Vector of MyAtoms.
• tmax: Time length of simulation.
• dt: Time step.
• ensemble: Ensemble object.
• algo: ODE solver algorithm (default: VelocityVerlet()).
• split: Number of segments (default: 1).
• kwargs: Additional keyword arguments.

Returns

• Processed trajectory or solution.

run(calc, bdys, tspan, dt, ensemble; algo=VelocityVerlet(), split=1, kwargs...)

Run an MD simulation for a set of atoms.

Arguments

• calc: Calculator object.
• bdys: Vector of MyAtoms.
• tspan: Time span tuple.
• dt: Time step.
• ensemble: Ensemble object.
• algo: ODE solver algorithm (default: VelocityVerlet()).
• split: Number of segments (default: 1).
• kwargs: Additional keyword arguments.

Returns

• Processed trajectory or solution.

show(io::IO, cell::MyCell)

Display cell struct information

Arguments

• io: IO
• cell: MyCell object

show(io::IO, traj::MyTraj)

Custom display for MyTraj objects.

Arguments

• io: IO stream.
• traj: MyTraj object.

Base.write(file::String, cell::MyCell)

Write a MyCell object to a file using Chemfiles.

Arguments

• file: Output file path.
• cell: MyCell object to write.

Side Effects

• Writes atomic coordinates, velocities, and cell information to file.

Base.write(file::String, traj::MyTraj; step=1)

Write a trajectory to a file using Chemfiles.

Arguments

• file: Output file path.
• traj: MyTraj object to write.
• step: Step interval for writing frames (default: 1).

Side Effects

• Writes trajectory frames, including positions, velocities, energies, and forces, to file.

Base.write(file::String, bdys::Vector{MyAtoms})

Write a vector of MyAtoms to a file using Chemfiles.

Arguments

• file: Output file path.
• bdys: Vector of MyAtoms to write.

Side Effects

• Writes atomic coordinates and velocities to file.

LinearAlgebra.rotate!(bdys::Vector{MyAtoms}, R::Matrix, about::Vector{Float64})

Rotate all atoms in bdys by rotation matrix R about a point about in-place.

Arguments

• bdys: Vector of MyAtoms objects.
• R: 3x3 rotation matrix.
• about: Point to rotate about.

LinearAlgebra.rotate!(bdys::Vector{MyAtoms}, R::Matrix)

Rotate all atoms in bdys by rotation matrix R in-place.

Arguments

• bdys: Vector of MyAtoms objects.
• R: 3x3 rotation matrix.

LinearAlgebra.rotate!(bdys::Vector{MyAtoms}, abc::Tuple{F,F,F}, about::Vector{F}) where F<:AbstractFloat

Rotate all atoms in bdys by Euler angles (α, β, γ) about a point about in-place.

Arguments

• bdys: Vector of MyAtoms objects.
• abc: Tuple of Euler angles (α, β, γ) in radians.
• about: Point to rotate about.

LinearAlgebra.rotate!(bdys::Vector{MyAtoms}, abc::Tuple{F,F,F}) where F <: AbstractFloat

Rotate all atoms in bdys by Euler angles (α, β, γ) in-place.

Arguments

• bdys: Vector of MyAtoms objects.
• abc: Tuple of Euler angles (α, β, γ) in radians.

CoM(pos, mas)

Compute the center of mass from positions and masses.

Arguments

• pos: Vector of position vectors.
• mas: Vector of masses.

Returns

• Center of mass as a vector.

CoM(bdys)

Compute the center of mass for a collection of atoms.

Arguments

• bdys: Vector of objects with fields m (mass) and r (position).

Returns

• Center of mass as a 3-element vector.

CO-CO Potential

Based on: Chen, Jun, et al. "Energy transfer between vibrationally excited carbon monoxide based on a highly accurate six-dimensional potential energy surface." The Journal of Chemical Physics 153.5 (2020).

Link: https://pubs.aip.org/aip/jcp/article/153/5/054310/1065758

Lennard Jones potential

MBX potentials

This allows uing all the potentials found within the MBX package.

MBX GitHub: https://github.com/paesanilab/MBX/tree/master

MBX Paper: https://pubs.aip.org/aip/jcp/article/159/5/054802/2904909/MBX-A-many-body-energy-and-force-calculator-for

CO-CO Potential

Based on: van Hemert, Marc C., Junko Takahashi, and Ewine F. van Dishoeck. "Molecular dynamics study of the photodesorption of CO ice." The Journal of Physical Chemistry A 119.24 (2015): 6354-6369.

Link: https://pubs.acs.org/doi/full/10.1021/acs.jpca.5b02611

SCME/f potential

This calls an ASE calculator of the SCME/f potential (not great) I still want to make a better wrapper. Idealy, one that calls the c++ routines directly (like MBX).

SCME Paper: https://pubs.rsc.org/en/content/articlehtml/2013/cp/c3cp52097h

SCME/f Paper: https://pubs.acs.org/doi/full/10.1021/acs.jctc.2c00598

Simple Point Charge (SPC) Models

SPC/F

Based on: Toukan, Kahled, and Aneesur Rahman. "Molecular-dynamics study of atomic motions in water." Physical Review B 31.5 (1985): 2643.

Link: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.31.2643

SPC/Fd

Based on: Dang, Liem X., and B. Montgomery Pettitt. "Simple intramolecular model potentials for water." Journal of physical chemistry 91.12 (1987): 3349-3354.

Link: https://doi.org/10.1021/j100296a048

SPC/Fw

Based on: Wu, Yujie, Harald L. Tepper, and Gregory A. Voth. "Flexible simple point-charge water model with improved liquid-state properties." The Journal of chemical physics 124.2 (2006).

Link: https://doi.org/10.1063/1.2136877

TIP4P/2005f

Based on: González, M. A., & Abascal, J. L. (2011). A flexible model for water based on TIP4P/2005. The Journal of chemical physics, 135(22).

Link: https://pubs.aip.org/aip/jcp/article/135/22/224516/190786

VDOS(inp; atms=nothing)

Compute the vibrational density of states (VDOS) from VACF input.

Arguments

• inp: vacfInps object.
• atms: (Optional) Indices of atoms to include.

Returns

• vacfOut object with VDOS data.

Compute the angular distribution function (ADF) between molecular orientations.

Arguments

• bdys::Vector{MyAtoms}: Vector of MyAtoms objects.
• kwargs...: Additional keyword arguments for kde_lscv.

Returns

• (x, y): Tuple of angle values (in degrees) and ADF.

animateMode(bdys::Vector{MyAtoms}, mode, fileName; c=1.0)

Animate a vibrational mode and write the trajectory to a file.

Arguments

• bdys: Vector of MyAtoms objects.
• mode: Mode vector to animate.
• fileName: Output file name.
• c: (Optional) Amplitude scaling factor (default: 1.0).

atomForces(frame, i)

Get the force vector for atom i in the given frame.

Arguments

• frame: Chemfiles Frame object.
• i: Atom index.

Returns

• Static vector of forces.

center!(cell)

Center the atoms in a cell.

Arguments

• cell: MyCell object.

Side Effects

• Modifies the cell in-place.

center(bdys::Vector{MyAtoms})

Compute the geometric center of a set of atoms.

Arguments

• bdys: Vector of MyAtoms.

Returns

• Center position as a vector.

centerBdys!(bdys::Vector{MyAtoms})

Center a set of atoms at the origin.

Arguments

• bdys: Vector of MyAtoms.

Side Effects

• Modifies positions in-place.

countNearestNeighbors(mol, bdys; rmax=4.5)

Count the number of neighboring molecules within a cutoff distance.

Arguments

• mol: The molecule of interest.
• bdys: Collection of molecules to search for neighbors.
• rmax: (Optional) Cutoff distance for neighbor search (default 4.5).

Returns

• Number of neighboring molecules within rmax of mol.

Compute the average number density of atoms in a given set.

Arguments

• bdys::Vector{MyAtoms}: Vector of MyAtoms objects representing atoms.

Returns

• Float64: Average number density (atoms per unit volume) within the maximum radial extent from the center.

Compute the average number density for a set of positions relative to a given center.

Arguments

• o::Vector{Float64}: The center point as a vector.
• pts::Vector{A}: Vector of position vectors (any subtype of AbstractArray).

Returns

• Float64: Average number density (points per unit volume) within the maximum radial extent from the center.

diffDotSqrt(v2, v1)

Compute the vector difference and its Euclidean norm between two vectors.

Arguments

• v2, v1: Input vectors.

Returns

• Tuple: (Euclidean distance, difference vector).

distanceMatrixAnyCell(cell::MyCell)

Compute the distance matrix for a general (possibly non-orthorhombic) cell.

Arguments

• cell: MyCell object.

Returns

• Symmetric matrix of distances between atoms.

distanceMatrixOrthorhombicCell(cell::MyCell)

Compute the distance matrix for an orthorhombic cell.

Arguments

• cell: MyCell object.

Returns

• Symmetric matrix of distances between atoms.

doRun(calc, vel, pos, tspan, simu, algo, dt, split; kwargs...)

Run an MD simulation, optionally splitting into segments.

Arguments

• calc: Calculator object.
• vel: Initial velocities.
• pos: Initial positions.
• tspan: Time span tuple.
• simu: Dynamics object.
• algo: ODE solver algorithm.
• dt: Time step.
• split: Number of segments.
• kwargs: Additional keyword arguments.

Returns

• Processed trajectory or solution.

dyn!(dv, v, u, p, t, calc)

Compute the time derivative for MD integration.

Arguments

• dv: Output derivative.
• v: Velocities.
• u: Positions.
• p: Dynamics object.
• t: Time.
• calc: Calculator object.

Side Effects

• Modifies dv in-place.

fg!(F, G, x, p, calc::MyCalc)

Evaluate energy and/or forces and gradients for optimization.

Arguments

• F: If not nothing, return energy.
• G: If not nothing, fill with gradients.
• x: Coordinate vector.
• p: Potential variables.
• calc: Calculator object.

Returns

• Energy if F is not nothing.

findPeaks(arr; min=0.0, max=1e30, width=1)

Find indices of local maxima (peaks) in an array.

Arguments

• arr: Array of numeric values to search for peaks.
• min: Minimum value threshold for a peak (default: 0.0).
• max: Maximum value threshold for a peak (default: 1e30).
• width: Minimum width for a peak (default: 1).

Returns

• Vector of indices where peaks are found.

findTurningPoints(arr)

Find indices of local maxima and minima (turning points) in an array.

Arguments

• arr: Array of numeric values.

Returns

• Vector of indices where turning points are found.

getAngle(r1, r2)

Compute the angle (in radians) between two vectors.

Arguments

• r1, r2: Input vectors.

Returns

• Angle in radians.

getDiffusionCoefficient(out; D=3)

Calculate the diffusion coefficient from VACF output.

Arguments

• out: vacfOut object.
• D: Dimensionality (default: 3).

Returns

• Diffusion coefficient (Float64).

getDistanceMatrix(cell::MyCell)

Compute the pairwise distance matrix for atoms in a cell, accounting for periodicity.

Arguments

• cell: MyCell object.

Returns

• Symmetric matrix of distances between atoms.

getForces(calc::MyCalc, cell::MyCell)

Compute the forces on all atoms in a cell using a calculator.

Arguments

• calc: Calculator object.
• cell: MyCell object.

Returns

• Vector of force vectors.

getForces(calc::MyCalc, bdys::Vector{MyAtoms})

Compute the forces on a set of atoms using a calculator.

Arguments

• calc: Calculator object.
• bdys: Vector of MyAtoms objects.

Returns

• Vector of force vectors.

getHarmonicFreqs(calc::MyCalc, obj::Union{MyCell, Vector{MyAtoms}})

Compute harmonic vibrational frequencies and modes for a cell or molecule.

Arguments

• calc: Calculator object (MyCalc).
• obj: MyCell or vector of MyAtoms.

Returns

• Tuple: (vector of frequencies, matrix of modes).

getIPR(modes; N=2)

Compute the inverse participation ratio (IPR) for vibrational modes.

Arguments

• modes: Matrix of mode vectors.
• N: Number of atoms per molecule (default: 2).

Returns

• Matrix of IPR values.

getImage(solu::SciMLBase.ODESolution, i::Int, dt::Float64)

Extract an Image from an ODE solution at a given index.

Arguments

• solu: ODE solution object.
• i: Index of the time step.
• dt: Time step size.

Returns

• Image object.

getModeInteractionPES(EoM!, bdys, mode; range=collect(-1:0.001:2))

Compute the interaction potential energy surface along a vibrational mode.

Arguments

• EoM!: Energy function.
• bdys: Vector of MyAtoms objects.
• mode: Mode vector.
• range: (Optional) Range of displacements (default: -1:0.001:2).

Returns

• Tuple: (displacement values, interaction energy values).

getModePES(EoM, bdys, mode; range=collect(-1:0.001:2))

Compute the potential energy surface (PES) along a vibrational mode.

Arguments

• EoM: Energy function.
• bdys: Vector of MyAtoms objects.
• mode: Mode vector.
• range: (Optional) Range of displacements (default: -1:0.001:2).

Returns

• Tuple: (displacement values, energy values).

getMols(cell::MyCell, rmax::Float64)

Cluster atoms in a cell into molecules using DBSCAN with cutoff rmax.

Arguments

• cell: MyCell object.
• rmax: Distance cutoff for clustering.

Returns

• Vector of vectors, each containing indices of atoms in a molecule.

getMols(bdys::Vector{MyAtoms}, rmax::Float64)

Cluster atoms in bdys into molecules using DBSCAN with cutoff rmax.

Arguments

• bdys: Vector of MyAtoms objects.
• rmax: Distance cutoff for clustering.

Returns

• Vector of vectors, each containing indices of atoms in a molecule.

getNewBdys(bdys, res)

Construct new atom objects from optimization results.

Arguments

• bdys: Original vector of MyAtoms.
• res: Optimization result.

Returns

• Vector of new MyAtoms objects.

getNumericalStress(calc::MyCalc, cell::MyCell; eps=1e-6)

Compute the numerical stress tensor for a cell using finite differences.

Arguments

• calc: Calculator object (MyCalc).
• cell: Cell object (MyCell).
• eps: Strain increment for finite difference (default: 1e-6).

Returns

• 3x3 stress tensor matrix.

getNumericalStressOrthogonal(calc::MyCalc, cell::MyCell; eps=1e-6)

Compute the numerical stress tensor for a cell using finite differences, only for diagonal terms (orthogonal cell).

Arguments

• calc: Calculator object (MyCalc).
• cell: Cell object (MyCell).
• eps: Strain increment for finite difference (default: 1e-6).

Returns

• 3x3 stress tensor matrix (only diagonal terms are nonzero).

getPR(ipr; x=1.6e-5)

Compute the participation ratio (PR) from IPR data.

Arguments

• ipr: IPR matrix.
• x: Threshold value (default: 1.6e-5).

Returns

• Vector of participation ratios.

getPos(cell)

Get Cartesian positions from scaled positions in a cell.

Arguments

• cell: MyCell object.

Returns

• Vector of Cartesian positions.

getPotEnergy(calc::MyCalc, obj::Union{MyCell, Vector{MyAtoms}})

Compute the potential energy of a cell or molecule.

Arguments

• calc: Calculator object (MyCalc).
• obj: MyCell or vector of MyAtoms.

Returns

• Potential energy (Float64).

Compute the radial distribution function (RDF) from a list of distances and a density.

Arguments

• d: Array of interatomic distances.
• ρ: Number density.
• kwargs...: Additional keyword arguments passed to kde_lscv.

Returns

• (x, y): Tuple of radius values x and normalized RDF values y.

getRotEnergy(mol::Vector{MyAtoms})

Compute the rotational kinetic energy of a molecule.

Arguments

• mol: Vector of MyAtoms.

Returns

• Rotational energy (Float64).

getRotationMatrix(α::F, β::F, γ::F) where F <: AbstractFloat

Construct a rotation matrix from Euler angles (α, β, γ).

Arguments

• α, β, γ: Euler angles in radians.

Returns

• 3x3 rotation matrix.

getScaledPos!(cell, x0)

Update scaled positions in a cell from Cartesian coordinates.

Arguments

• cell: MyCell object.
• x0: Cartesian coordinates.

Side Effects

• Modifies the cell in-place.

getScaledPos(x0, lattice)

Get scaled positions from Cartesian coordinates and lattice.

Arguments

• x0: Cartesian coordinates.
• lattice: Lattice matrix.

Returns

• Vector of scaled positions.

getScaledPos(bdys::Vector{MyAtoms}, lattice)

Get scaled positions for a set of atoms given a lattice.

Arguments

• bdys: Vector of MyAtoms.
• lattice: Lattice matrix.

Returns

• Vector of scaled positions.

getSurfaceMolecules(bdys::Vector{MyAtoms}; α=nothing)

Get the surface molecules from a set of atoms using alpha shapes.

Arguments

• bdys: Vector of MyAtoms.
• α: Alpha parameter (optional).

Returns

• Vector of surface MyAtoms.

getTransEnergy(mol::Vector{MyAtoms})

Compute the translational kinetic energy of a molecule.

Arguments

• mol: Vector of MyAtoms.

Returns

• Translational energy (Float64).

getVelMas(tj::MyTraj)

Get all velocities and masses from a trajectory.

Arguments

• tj: Traj object.

Returns

• Tuple: (vector of velocities, vector of masses)

getVibEnergy(mol::Vector{MyAtoms}, eignvec; calc=nothing)

Compute the vibrational energy of a molecule along a mode.

Arguments

• mol: Vector of MyAtoms.
• eignvec: Mode vector.
• calc: (Optional) Calculator for potential energy.

Returns

• Vibrational energy (Float64).

getVolume(cell)

Compute the volume of a cell.

Arguments

• cell: MyCell object.

Returns

• Volume (Float64).

hiddenEoM(F, G, Γ, calc::MyCalc, vars, x)

Energy and gradient evaluation for hidden variable optimization.

Arguments

• F: Energy output (or nothing).
• G: Gradient output (or nothing).
• Γ: Gradient buffer.
• calc: Calculator object.
• vars: HiddenOptVars object.
• x: Coordinate vector.

Returns

• Energy value if F is not nothing.

hiddenOpt(calc::MyCalc, algo, cell, T; kwargs...)

Optimize a cell using a hidden variable approach and a supercell transformation.

Arguments

• calc: Calculator object.
• algo: Optimization algorithm.
• cell: MyCell object.
• T: Transformation matrix.
• kwargs: Additional options.

Returns

• Optimized MyCell object.

ifProperty(frame, props, p)

Return the value of property p from frame if it exists in props, else return 0.0.

Arguments

• frame: Chemfiles Frame object.
• props: List of property names.
• p: Property name to look for.

Returns

• Value of the property as Float64, or 0.0 if not found.

makeBdys(cell::MyCell)::Vector{MyAtoms}

Convert a cell to a vector of MyAtoms.

Arguments

• cell: MyCell object.

Returns

• Vector of MyAtoms.

makeBdys(tj::MyTraj, i::Int)

Construct a vector of MyAtoms from a trajectory at a given image index.

Arguments

• tj: Traj object.
• i: Image index.

Returns

• Vector of MyAtoms.

makeCell(bdys, lattice; mask, PBC, NC)

Construct a Cell from a vector of MyAtoms and a lattice.

Arguments

• bdys: Vector of MyAtoms.
• lattice: Lattice matrix.
• mask: Mask vector (optional).
• PBC: Periodic boundary conditions (optional).
• NC: Neighbor counts (optional).

Returns

• Cell object.

makeSuperCell!(super, cell, T)

In-place creation of a supercell from a cell and transformation matrix.

Arguments

• super: Supercell object to fill.
• cell: Cell to replicate.
• T: Transformation matrix.

Side Effects

• Modifies the supercell in-place.

makeSuperCell(cell, T)

Create a supercell from a cell and transformation matrix.

Arguments

• cell: MyCell object.
• T: Transformation matrix.

Returns

• New supercell object.

mirror!(out)

Mirror the VACF output for improved frequency resolution.

Arguments

• out: vacfOut object.

mkvar(x)

Evaluate a symbol from a string and return its value.

Arguments

• x: String representing the variable name.

Returns

• Value of the variable with name x.

myRepeat(A::Vector{MVector{D,Float64}}, count::Integer, mask::Vector{Bool}) where D

Repeat elements of a vector of static vectors, excluding masked elements, and return a deep copy.

Arguments

• A: Vector of MVector{D,Float64}.
• count: Number of times to repeat unmasked elements.
• mask: Boolean mask vector (true = keep, false = repeat).

Returns

• Vector of repeated and copied static vectors.

myRepeat(A::Vector{T}, count::Integer, mask::Vector{Bool}) where T <: Union{String, Number}

Repeat elements of a vector, excluding masked elements, and concatenate with the original.

Arguments

• A: Input vector.
• count: Number of times to repeat unmasked elements.
• mask: Boolean mask vector (true = keep, false = repeat).

Returns

• Concatenated vector with repeated elements.

opt(calc::MyCalc, algo, cell::MyCell; kwargs...)

Optimize the geometry of a cell.

Arguments

• calc: Calculator object.
• algo: Optimization algorithm.
• cell: MyCell object.
• kwargs: Additional options.

Returns

• Optimized MyCell object.

opt(calc::MyCalc, algo, bdys::Vector{MyAtoms}; kwargs...)

Optimize the geometry of a set of atoms.

Arguments

• calc: Calculator object.
• algo: Optimization algorithm.
• bdys: Vector of MyAtoms objects.
• kwargs: Additional options.

Returns

• Optimized vector of MyAtoms.

optCell(calc::MyCalc, algo, cell::MyCell; precon=nothing, kwargs...)

Optimize the lattice parameters of a cell.

Arguments

• calc: Calculator object.
• algo: Optimization algorithm.
• cell: MyCell object.
• precon: (Optional) Preconditioner.
• kwargs: Additional options.

Returns

• Optimized MyCell object.

periodicDistance(x::AbstractArray, y::AbstractArray, vects)

Compute the minimum periodic distance between two points given lattice vectors.

Arguments

• x, y: Position vectors.
• vects: Iterable of lattice vectors.

Returns

• Minimum periodic distance (Float64).

pickRandomMol(bdys::Vector{MyAtoms}, loc)

Pick a random molecule from the surface or bulk.

Arguments

• bdys: Vector of MyAtoms.
• loc: "surf" or "bulk".

Returns

• Vector of MyAtoms for the selected molecule.

prep4pot(builder, cell::MyCell)

Prepare variables for potential energy calculation from a cell.

Arguments

• builder: Potential builder function.
• cell: MyCell object.

Returns

• Tuple: (coordinate vector, optVars object).

prep4pot(builder, bdys::Vector{MyAtoms})

Prepare variables for potential energy calculation from atoms.

Arguments

• builder: Potential builder function.
• bdys: Vector of MyAtoms objects.

Returns

• Tuple: (coordinate vector, optVars object).

prepX0(cell::MyCell)

Prepare the initial coordinate vector from a cell.

Arguments

• cell: MyCell object.

Returns

• Flat vector of coordinates.

prepX0(bdys::Vector{MyAtoms})

Prepare the initial coordinate vector from a set of atoms.

Arguments

• bdys: Vector of MyAtoms objects.

Returns

• Flat vector of coordinates.

processDynamics(solu::SciMLBase.ODESolution; dt=fs, step=1)

Convert an ODE solution to a Traj object.

Arguments

• solu: ODE solution object.
• dt: Time step (default: fs).
• step: Step interval (default: 1).

Returns

• Traj object.

processTmpFiles(files; kwargs...)

Process a list of temporary files containing ODE solutions into a single trajectory.

Arguments

• files: List of file paths.
• kwargs: Additional keyword arguments.

Returns

• Traj object.

randRotate!(bdys::Vector{MyAtoms}, about::Vector{Float64})

Apply a random rotation about a point about to all atoms in bdys in-place.

Arguments

• bdys: Vector of MyAtoms objects.
• about: Point to rotate about.

randRotate!(bdys::Vector{MyAtoms})

Apply a random rotation to all atoms in bdys in-place.

Arguments

• bdys: Vector of MyAtoms objects.

Compute the radial distribution function for pairs of two specified atomic species.

Arguments

• bdys::Vector{MyAtoms}: Vector of MyAtoms objects.
• P::Pair{String, String}: Pair of atomic species labels (A, B).
• kwargs...: Additional keyword arguments for getRdf.

Returns

• (x, y): Tuple of radius values and RDF for the species pair.

Compute the radial distribution function for all pairs of a given atomic species.

Arguments

• bdys::Vector{MyAtoms}: Vector of MyAtoms objects.
• A::String: Atomic species label.
• kwargs...: Additional keyword arguments for getRdf.

Returns

• (x, y): Tuple of radius values and RDF for the given species.

Compute the radial distribution function between molecular centers of mass.

Arguments

• bdys::Vector{MyAtoms}: Vector of MyAtoms objects.
• rmol: Distance threshold for molecular grouping (default 1.2).
• kwargs...: Additional keyword arguments for getRdf.

Returns

• (x, y): Tuple of radius values and RDF.

readFrame(frame::Frame)

Convert a Chemfiles Frame to a vector of MyAtoms or a MyCell if lattice is present.

Arguments

• frame: Chemfiles Frame object.

Returns

• Vector of MyAtoms or MyCell object.

readImage(frame::Frame)

Read an image (snapshot) from a Chemfiles Frame, extracting positions, velocities, forces, and properties.

Arguments

• frame: Chemfiles Frame object.

Returns

• Image object containing positions, velocities, time, temperature, energy, and forces.

readSystem(file::String)

Read a system from a file and return either a trajectory or a single frame.

Arguments

• file: Path to the file.

Returns

• Traj object if multiple frames, otherwise a single frame as MyCell or MyAtoms.

readTraj(buf::Trajectory, N::Int)

Read a trajectory from a Chemfiles Trajectory buffer.

Arguments

• buf: Chemfiles Trajectory object.
• N: Number of frames to read.

Returns

• Traj object containing all images, masses, symbols, and lattice.

reducedMass(bdys)

Compute the reduced mass for a collection of atoms.

Arguments

• bdys: Vector of objects with field m (mass).

Returns

• Reduced mass (Float64).

reducedMass(mas::Vector{Float64})

Compute the reduced mass from a vector of masses.

Arguments

• mas: Vector of masses.

Returns

• Reduced mass (Float64).

reorder!(cell::MyCell, order::Vector{Int})

Reorder the atoms in a cell according to a given order.

Arguments

• cell: MyCell object.
• order: New order of indices.

Side Effects

• Modifies the cell in-place.

replicate!(super, cell, N)

Replicate a cell into a supercell.

Arguments

• super: Supercell object to fill.
• cell: Cell to replicate.
• N: Replication factors along each axis.

Side Effects

• Modifies the supercell in-place.

savGol(y, ws, order; deriv=0)

Apply a Savitzky-Golay filter to the input signal y.

Arguments

• y: Array of data points to be smoothed or differentiated.
• ws: Window size (must be odd and ≥ 1).
• order: Polynomial order for the filter (must satisfy ws ≥ order + 2).
• deriv: (Optional) Order of the derivative to compute (default is 0, i.e., smoothing).

Returns

• Filtered (or differentiated) signal as an array of the same length as y.

Throws

• ArgumentError if input arguments are invalid.

Example

smoothed = savGol(data, 5, 2)

singleRun(calc, vel, pos, tspan, simu, algo, dt; kwargs...)

Run a single MD simulation segment.

Arguments

• calc: Calculator object.
• vel: Initial velocities.
• pos: Initial positions.
• tspan: Time span tuple.
• simu: Dynamics object.
• algo: ODE solver algorithm.
• dt: Time step.
• kwargs: Additional keyword arguments.

Returns

• ODE solution object.

st!(F, G, x, cell::MyCell, calc::MyCalc; precon=nothing, diag=false)

Evaluate stress and/or energy for cell optimization.

Arguments

• F: If not nothing, return energy.
• G: If not nothing, fill with gradients.
• x: Lattice vector.
• cell: MyCell object.
• calc: Calculator object.
• precon: Preconditioner (optional).
• diag: Use only diagonal terms (default: false).

Returns

• Energy if F is not nothing.

swapAtoms!(bdys::Vector{MyAtoms}, i, j)

Swap the positions of two atoms in a vector.

Arguments

• bdys: Vector of MyAtoms.
• i: Index of first atom.
• j: Index of second atom.

Side Effects

• Modifies the positions in-place.

swapIso!(bdys::Vector{MyAtoms}, swap, mas)

Swap isotopes (masses) for a set of atoms.

Arguments

• bdys: Vector of MyAtoms.
• swap: Indices to swap.
• mas: New masses.

Side Effects

• Modifies masses in-place.

transExcite!(mol::Vector{MyAtoms}, ke)

Excite the translational motion of a molecule to a given kinetic energy.

Arguments

• mol: Vector of MyAtoms.
• ke: Target kinetic energy.

Side Effects

• Modifies velocities of atoms in-place.

translate!(bdys::Vector{MyAtoms}, v::Vector{Float64})

Translate all atoms in bdys by vector v in-place.

Arguments

• bdys: Vector of MyAtoms objects.
• v: Translation vector.

vCoM(vel, mas)

Compute the center of mass velocity from velocities and masses.

Arguments

• vel: Vector of velocity vectors.
• mas: Vector of masses.

Returns

• Center of mass velocity as a vector.

vCoM(bdys)

Compute the center of mass velocity for a collection of atoms.

Arguments

• bdys: Vector of objects with fields m (mass) and v (velocity).

Returns

• Center of mass velocity as a vector.

vacf!(inp, out; atms=nothing)

Compute the velocity autocorrelation function (VACF).

Arguments

• inp: vacfInps object.
• out: vacfOut object.
• atms: (Optional) Indices of atoms to include.

vibExcite!(mol::Vector{MyAtoms}, eignvec, E)

Excite a vibrational mode of a molecule to a given energy.

Arguments

• mol: Vector of MyAtoms.
• eignvec: Mode vector.
• E: Target energy.

Side Effects

• Modifies velocities of atoms in-place.

window!(out, W)

Apply a window function to the VACF output.

Arguments

• out: vacfOut object.
• W: Window function.

wrap!(cell)

Wrap all atoms in a cell into the primary unit cell.

Arguments

• cell: MyCell object.

Side Effects

• Modifies the cell in-place.

wrap!(bdys::Vector{MyAtoms}, lattice)

Wrap all atoms into the primary unit cell.

Arguments

• bdys: Vector of MyAtoms.
• lattice: Lattice matrix.

Side Effects

• Modifies positions in-place.

zeroVCoM!(bdys)

Remove the center of mass velocity from a collection of atoms in-place.

Arguments

• bdys: Vector of objects with fields m (mass) and v (velocity).

Side Effects

• Modifies velocities in-place to set total momentum to zero.