Crib File
Return to top-level of LAMMPS documentation.
This file contains one-line descriptions of the key variables and 
parameters used in LAMMPS. The variables are listed by their data type:
Note: this file is somewhat out-of-date for LAMMPS 99.
    - 
    maxown = max # of local owned atoms 
    
- 
    maxother = max # of local nearby atoms 
    
- 
    maxtotal = max # of total atoms in simulation 
    
- 
    maxtype = max # of atom types 
    
- 
    maxbond = max # of bonds to compute on one processor
    
- 
    maxangle = max # of angles to compute on one processor 
    
- 
    maxdihed = max # of dihedrals to compute on one processor 
    
- 
    maximpro = max # of impropers to compute on one processor 
    
- 
    maxbondper = max # of bonds of one atom 
    
- 
    maxangleper = max # of angles of one atom 
    
- 
    maxdihedper = max # of dihedrals of one atom 
    
- 
    maximproper = max # of impropers of one atom 
    
- 
    maxbondtype = max # of bond types 
    
- 
    maxangletype = max # of angle types 
    
- 
    maxdihedtype = max # of dihedral types 
    
- 
    maximprotype = max # of improper types 
    
- 
    maxexch = max # of atoms in exchange buffer 
    
- 
    maxsend = max # of atoms to send to all neighbors in all swaps 
    
- 
    maxsendone = max # of atoms to send in one swap 
    
- 
    maxswap = max # of swaps to do at each timestep 
    
- 
    maxneigh = max # of neighbors per owned atom 
    
- 
    maxsneigh = max # of special neighbors of one atom 
    
- 
    maxbin = max # of local neighbor bins 
    
- 
    maxfix = max # of defined constraints + 1
    
- 
    maxdiag = max # of diagnostic routines 
    
- 
    maxgrid = max size of PPPM grid with ghosts on one processor 
    
- 
    maxfft = max size of PPPM FFT grid on one processor 
    
- 
    maxperatom = max # of data items stored/comm/output per atom 
    
- 
    maxatom = maxown + maxother = total # of own and nearby atoms 
    
- 
    maxexchtot = maxexch * (maxperatom + maxsneigh + 3*maxbondper + 
    4*maxangleper + 5*maxdihedper + 5*maximproper) = total data volume for 
    all exchanged atoms 
    
- 
    maxrestot = maxown * (maxperatom - 3 + 3*maxbondper + 4*maxangleper + 
    5*maxdihedper + 5*maximproper)+1 = total data volume for all buffered 
    restart atoms 
    
- 
    maxsendspec = 2 * maxsneigh * maxown total data volume for sending 
    special requests 
    
- 
    maxrecvspec = maxsneigh + 1 total data volume for receiving a list of 
    specials 
    - 
    anglecoeff(2,maxangletype) = angle coeffs for each angle type 
    
- 
    bondcoeff(5,maxbondtype) = bond coeffs for each bond type 
    
- 
    boundhi(maxswap) = hi slab boundary on atom positions for each swap 
    send 
    
- 
    boundlo(maxswap) = lo slab boundary on atom positions for each swap 
    send 
    
- 
    buf1(maxexchtot) = comm buffer for sending exchange atoms 
    
- 
    buf2(2*maxexchtot) = comm buffer for 2 recv of exchange atoms 
    
- 
    buf3(3*maxsendone) = comm buffer for sending one set of swap atom 
    positions 
    
- 
    buf4(8*maxown) = comm buffer for output 
    
- 
    buf5(maxrestot) = comm buffer for restart atoms 
    
- 
    buf6(maxsendone) = comm buffer for sending one set of swap charges 
    
- 
    cutforcesq(maxtype,maxtype) = force cutoff squared for atom pair 
    (LJ/Coul) 
    
- 
    cutljsq(maxtype,maxtype) = LJ cutoff squared for atom pairs 
    
- 
    cutljinner(maxtype,maxtype) = inner LJ cutoff for switched LJ 
    
- 
    cutljinnersq(maxtype,maxtype) = inner LJ cutoff squared for switched LJ 
    
- 
    cutneighsq(maxtype,maxtype) = neigh cutoff squared for atom pair 
    (LJ/Coul + skin) 
    
- 
    diagparams(6,maxdiag) = parameters to pass into a diagnostic routine 
    
- 
    dihedcoeff(3,maxdihedtype) = dihedral coeffs for each dihedral type 
    
- 
    f(3,maxown) = forces on own atoms 
    
- 
    fixcoeff(8,maxfix) = constraint coeffs for each constraint 
    
- 
    fixstore(5*maxfix) = accumulated quantities for each constraint 
    
- 
    improcoeff(2,maximprotype) = improper coeffs for each improper type 
    
- 
    lj12345(maxtype,maxtype) = pre-computed LJ coeffs for use in energy and 
    force 
    
- 
    ljsw01234(maxtype,maxtype) = pre-computed switched LJ coeffs for eng 
    and force 
    
- 
    mass(maxtype) = mass of each atom type 
    
- 
    noncoeff1234(maxtype,maxtype) = nonbond coeffs input for atom pairs 
    
- 
    offset(maxtype,maxtype) = LJ potential offsets at cutoff for energy 
    calc 
    
- 
    q(maxatom) = charge of own and nearby atoms (electron units) 
    
- 
    v(3,maxown) = velocity of owned atoms 
    
- 
    x(3,maxatom) = positions of own and nearby atoms 
    
- 
    xhold(3,maxown) = positions of own atoms at last reneighboring 
    - 
    angleatom123(maxangleper,maxown) = angle atoms for angles of owned 
    atoms 
    
- 
    anglelist(4,maxangle) = atoms and type of each angle to compute locally 
    
- 
    angletype(maxangleper,maxown) = angle type for angles of owned atoms 
    
- 
    bin(maxatom) = linked list pointers from one atom to next in bin 
    
- 
    binpnt(maxbin) = pointer to 1st atom in each bin 
    
- 
    bondatom12(maxbondper,maxown) = bond atoms for bonds of owned atoms 
    
- 
    bondlist(3,maxbond) = atoms and type of each bond to compute locally 
    
- 
    bondtype(maxbondper,maxown) = bond type for bonds of owned atoms 
    
- 
    bondtypeflag(maxbondtype) = flag for whether bond coeffs are set 
    
- 
    diagfileflag(maxdiag) = whether a file has been specified for a diag 
    routine 
    
- 
    diagfreq(maxdiag) = call a diagnostic routine every this many steps 
    
- 
    diagnparams(maxdiag) = # of parameters specified for a diagnostic 
    routine 
    
- 
    diagstyle(maxdiag) = whether a diagnostic has been set 0/1 
    
- 
    dihedatom1234(maxdihedper,maxown) = dihed atoms for diheds of owned 
    atoms 
    
- 
    dihedlist(5,maxdihed) = atoms and type of each dihedral to compute 
    locally 
    
- 
    dihedtype(maxdihedper,maxown) = dihed type for diheds of owned atoms 
    
- 
    fix(maxown) = constraint assignments for each owned atom 
    
- 
    fixflag(3,maxfix) = 0/1 flags for various fix styles 
    
- 
    fixptr(maxfix) = how many values are accumulated for each constraint 
    
- 
    fixstyle(maxfix) = style of each constraint 
    
- 
    ibuf1(maxsendone) = comm buffer for sending one set of swap atom tags 
    
- 
    ibuf2(maxsendone) = comm buffer for sending one set of swap atom types 
    
- 
    ibuf3(maxspec) = comm buffer for sending special requests 
    
- 
    ibuf4(maxspec) = comm buffer for receiving special lists 
    
- 
    improatom1234(maximproper,maxown) = impro atoms for impros of owned 
    atoms 
    
- 
    improlist(5,maximpro) = atoms and type of each improper to compute 
    locally 
    
- 
    improtype(maximproper,maxown) = impro type for impros of owned atoms 
    
- 
    list(maxown) = linked list of local atoms (last one -> maxown+1) 
    
- 
    localptr(0:maxtotal) = ptr from global atom to local array (0 if don't 
    have) 
    
- 
    molecule(maxown) = molecule id # each owned atom is in 
    
- 
    nlist(maxown*maxneigh+maxneigh) = neighbor lists of own atoms 
    
- 
    nliststart(maxown) = pointer to where neighbor list for this atom 
    starts 
    
- 
    nliststop(maxown) = pointer to where neighbor list for this atom stops 
    
- 
    nontypeflag(maxtype,maxtype) = flag for whether nonbond coeffs are set 
    
- 
    nrlist(maxswap+1) = prt to where received other atoms start for each 
    swap 
    
- 
    nslist(maxswap+1) = pointer to where swap list starts for each swap 
    
- 
    numangle(maxown) = # of angles of each owned atom 
    
- 
    numbond(maxown) = # of 1st neighbors bonded to each owned atom 
    
- 
    num2bond(maxown) = # of 2nd neighbors for each owned atom 
    
- 
    num3bond(maxown) = # of 3rd neighbors for each owned atom 
    
- 
    numdihed(maxown) = # of dihedrals of each owned atom 
    
- 
    numimpro(maxown) = # of impropers of each owned atom 
    
- 
    rpart(maxswap) = node # of who to recv from for each swap 
    
- 
    slist(maxsend) = send list of atoms to send out in all swaps 
    
- 
    spart(maxswap) = node # of who to send to for each swap 
    
- 
    specbond(maxsneigh,maxown) = special bond neighbors of each owned atom 
    
- 
    tag(maxatom) = global id # of own and nearby atoms 
    
- 
    true(maxown) = which periodic box atom is truly in for all 3 dims 
    
- 
    type(maxatom) = type # of own and nearby atoms 
    
- 
    typecheck(maxtype) = consistency check for all existing atom types 
    
- 
    typechecktmp(maxtype) = summing array for atom type consistency check 
    
- 
    velflag(maxown) = whether velocity for each atom has been created 
    - 
    binsize[xyz] = size of global neighbor bins in each dimension 
    
- 
    boltz = Boltzmann factor 
    
- 
    border(2,3) = lo/hi boundaries of my sub-box in each dimension 
    
- 
    coulpre = Coulombic force prefactor 
    
- 
    createregion(6) = bounding box for atoms to create temperature for 
    
- 
    createvec(3) = initial velocity for create temp atoms 
    
- 
    cutcoul = input force cutoff for Coulombic interactions 
    
- 
    cutcoulsq = Coul cutoff squared for all atom pairs 
    
- 
    cutforce = max force cutoff for all atom pairs (LJ/Coul) 
    
- 
    cutlj = input global (default) LJ cutoff for all atom pairs 
    
- 
    cutljinterior = global inner LJ cutoff for switched LJ 
    
- 
    cutneigh = max neighbor cutoff for all atom pairs (LJ/Coul + skin) 
    
- 
    dielectric = dielectric constant 
    
- 
    dt = timestep 
    
- 
    dtfactor = timestep conversion factor from input to program units 
    
- 
    dthalf = timestep / 2 
    
- 
    efactor = energy conversion factor from Coulombic to Kcals 
    
- 
    e_angle = energy in angles 
    
- 
    e_bond = energy in bonds 
    
- 
    e_coul = energy in nonbond Coulombic 
    
- 
    e_dihedral = energy in dihedrals 
    
- 
    e_improper = energy in impropers 
    
- 
    e_total = total energy 
    
- 
    e_vdwl = energy in nonbond LJ 
    
- 
    fixregion(6) = bounding box for atoms to assign to a constraint 
    
- 
    skin = distance between force and neighbor cutoffs 
    
- 
    special(3) = weight factors for special neighbors 
    
- 
    triggersq = squared distance to trigger neighbor list rebuild 
    
- 
    two16 = 2 ^ (1/6) constant for use in FENE bond potentials 
    
- 
    t_create = requested initialization temp 
    
- 
    t_current = current temp returned from temp routine 
    
- 
    t_nph = default temp for constant NPH 
    
- 
    t_start = target temp at beginning of run 
    
- 
    t_stop = target temp at end of run 
    
- 
    t_window = control temp within this window 
    
- 
    time_angle = angle time 
    
- 
    time_bond = bond time 
    
- 
    time_comm = communication time 
    
- 
    time_current = current time 
    
- 
    time_dihedral = dihedral time 
    
- 
    time_exch = exchange time 
    
- 
    time_improper = improper time 
    
- 
    time_io = i/o time 
    
- 
    time_loop = time for integration loop 
    
- 
    time_neigh1 = neighboring time in nonbond 
    
- 
    time_neigh2 = neighboring time in bonds 
    
- 
    time_nonbond = nonbond force time 
    
- 
    time_other = other miscellaneous time 
    
- 
    time_total = total run time of entire simulation 
    
- 
    x[yz]mc = box size minus force cutoff for PBC checks 
    
- 
    x[yz]ms box size minus neighbor list cutoff for PBC checks 
    
- 
    x[yz]boundlo = lower global box boundary in each dimension 
    
- 
    x[yz]boundhi = upper global box boundary in each dimension 
    
- 
    x[yz]prd = global box size in each dimension 
    - 
    atompnt = pointer to 1st atom in my list 
    
- 
    bondstyle = style of bond computation 
    
- 
    boxflag = flag if box has been remapped (non-PBC) 
    
- 
    coulstyle = style of Coulomb interaction 
    
- 
    creategroup = kind of atom group to create temp for 
    
- 
    createstyle = style of temp creation 
    
- 
    createtypehi = upper range of atom types to create temp for 
    
- 
    createtypelo = lower range of atom types to create temp for 
    
- 
    dumpfileflag = has dump file been opened or not (1/0) 
    
- 
    dumpflag = dump atoms to file every this many steps (0 = never) 
    
- 
    dumpforcefileflag = has dump force file been opened or not (1/0) 
    
- 
    dumpforceflag = dump forces to file every this many steps (0 = never) 
    
- 
    dumpvelfileflag = has dump velocity file been opened or not (1/0) 
    
- 
    dumpvelflag = dump vels to file every this many steps (0 = never) 
    
- 
    fixatom = assign atom/molecule with this tag to a constraint 
    
- 
    fixgroup = kind of atom group to assign to a constraint 
    
- 
    fixnum = total # of accumulated values for all constraints 
    
- 
    fixtype = assign group of atoms of this type to a constraint 
    
- 
    fixwhich = which constraint a atom group is to be assigned to 
    
- 
    freepnt = pointer to 1st free space in list (last one -> 0) 
    
- 
    idimension = dimension of problem (2-d or 3-d) 
    
- 
    iseed = RNG seed for generating initial velocities 
    
- 
    itime = current timestep loop counter in integrator 
    
- 
    iversion = version number of restart files (for backward compat) 
    
- 
    max_angle = most angles I ever have to compute 
    
- 
    max_angleper = most angles ever attached to any atom 
    
- 
    max_bond = most bonds I ever have to compute 
    
- 
    max_bondper = most bonds ever attached to any atom 
    
- 
    max_dihed = most diheds I ever have to compute 
    
- 
    max_dihedper = most diheds ever attached to any atom 
    
- 
    max_exch = most atoms ever leaving my box (in one dimension) 
    
- 
    max_impro = most impros I ever have to compute 
    
- 
    max_improper = most impros ever attached to any atom 
    
- 
    max_nlocal = most atoms I ever owned 
    
- 
    max_neigh = most neighbors ever stored in neighbor list 
    
- 
    max_nother = most nearby atoms I ever stored 
    
- 
    max_slist = biggest size swap list ever reached 
    
- 
    max_swap = most atoms ever sent in one swap 
    
- 
    mbin[xyz] = # of bins in my box with nearby atoms included 
    
- 
    mbin[xyz]lo = global bin indices (offset) at corner of extended box 
    
- 
    me(3) = which box I am (0 - pgrid-1) in each dimension 
    
- 
    mixflag = whether mixing style has been set or not 
    
- 
    mixstyle = style of mixing for nonbond coeffs (arith,geom,sixth) 
    
- 
    mpart(2,3)= node # of neighbor processor in each dimension 
    
- 
    nanglelocal = local # of angless to compute 
    
- 
    nangles = total # of angles 
    
- 
    nangletypes = total # of angle types 
    
- 
    natoms = total # of atoms 
    
- 
    nbin[xyz] # of global neighbor bins in each dimension 
    
- 
    nbondlocal = local # of bonds to compute 
    
- 
    nbonds = total # of bonds 
    
- 
    nbondtypes = total # of bond types 
    
- 
    ndanger = # of neighbor rebuilds triggered by 1st check 
    
- 
    ndiags = # of user-specified diagnostic routines 
    
- 
    ndihedlocal = local # of dihedrals to compute 
    
- 
    ndihedrals = total # of diheds 
    
- 
    ndihedtypes = total # of dihedral types 
    
- 
    need(3) how many processors I need neighbors from in each dim 
    
- 
    neighago = how many timesteps ago neighboring was done 
    
- 
    neighdelay = delay neighbor list build for this many steps 
    
- 
    neighfreq = build neighbor list every this many steps 
    
- 
    neighstyle = neighboring by (0) N^2 or (1) binning method 
    
- 
    neightop = last used position in neighbor list (nlist) 
    
- 
    neightrigger = always (0) do neighbor list or trigger (1) on atom move 
    
- 
    newton = flag for kind of Newton's 3rd law used (0,1,2,3) 
    
- 
    newton_bond = Newton's 3rd is not used (0) or (1) used for bonds 
    
- 
    newton_nonbond = Newton's 3rd is not used (0) or (1) used for nonbonds 
    
- 
    nfixes = # of constraints 
    
- 
    nimprolocal = local # of impropers to compute 
    
- 
    nimpropers = total # of impros 
    
- 
    nimprotypes = total # of improper types 
    
- 
    nlocal = # of atoms I currently own 
    
- 
    nother = # of nearby atoms I currently store 
    
- 
    node = my node # 
    
- 
    nonstyle = style on nonbond computation 
    
- 
    nprocs = total # of processors 
    
- 
    nsteps = # of timesteps to simulate 
    
- 
    nswap = # of swaps at each timestep 
    
- 
    ntimestep = current global timestep 
    
- 
    ntypes = total # of atom types 
    
- 
    numneigh = number of times reneighboring is done 
    
- 
    offsetflag = whether to include energy offset in LJ energy calc 
    
- 
    peratom = # of values/atom not including bond info 
    
- 
    perflagx[yz] = flag for periodic (0) or non-periodic (1) BC 
    
- 
    pgrid(3) = # of processors in each dimension 
    
- 
    readflag = whether atom input file has been read or not (1/0) 
    
- 
    restartfileflag = which restart file to open next (0/1) 
    
- 
    restartflag = write restart file every this many steps (0=never) 
    
- 
    t_every = rescale/replace temp every this many steps 
    
- 
    tempflag = constant temperature style flag 
    
- 
    thermoflag = print thermo info every this many steps (0 = never) 
    
- 
    thermostyle = style of thermo output (0 = full, 1 = reduced) 
    
- 
    trueflag = whether to dump remapped or true atom positions 
    
- 
    units = flag for real vs reduced LJ units 
    - 
    datafile = file to read atom and connectivity info from 
    
- 
    diagfile(maxdiag) = files to print user-specified diagnostics to 
    
- 
    diagname(maxdiag) = name of a user-specified diagnostic routine 
    
- 
    dumpfile = file to dump atom info to 
    
- 
    dumpforcefile = file to dump force info to 
    
- 
    dumpvelfile = file to dump velocity info to 
    
- 
    restart_in = file to read restart info from 
    
- 
    restart_out[12] = files to write restart info to