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36 #ifndef GMX_MDLIB_CALC_VERLETBUF_H
37 #define GMX_MDLIB_CALC_VERLETBUF_H
39 #include "gromacs/utility/basedefinitions.h"
40 #include "gromacs/utility/real.h"
51 int cluster_size_i; /* Cluster pair-list i-cluster size atom count */
52 int cluster_size_j; /* Cluster pair-list j-cluster size atom count */
53 } verletbuf_list_setup_t;
56 /* Add a 5% and 10% rlist buffer for simulations without dynamics (EM, NM, ...)
57 * and NVE simulations with zero initial temperature, respectively.
58 * 10% should be enough for any NVE simulation with PME and nstlist=10,
59 * for other settings it might not be enough, but then it's difficult
60 * to come up with any reasonable (not crazily expensive) value
61 * and grompp will notify the user when using the 10% buffer.
63 static const real verlet_buffer_ratio_nodynamics = 0.05;
64 static const real verlet_buffer_ratio_NVE_T0 = 0.10;
67 /* Sets the pair-list setup assumed for the current Gromacs configuration.
68 * The setup with smallest cluster sizes is return, such that the Verlet
69 * buffer size estimated with this setup will be conservative.
70 * makeSimdPairList tells if to take into account SIMD, when supported.
71 * makeGpuPairList tells to estimate for GPU kernels (makeSimdPairList is ignored with makeGpuPairList==true)
73 void verletbuf_get_list_setup(bool makeSimdPairList,
75 verletbuf_list_setup_t *list_setup);
78 /* Calculate the non-bonded pair-list buffer size for the Verlet list
79 * based on the particle masses, temperature, LJ types, charges
80 * and constraints as well as the non-bonded force behavior at the cut-off.
81 * The pair list update frequency and the list lifetime, which is nstlist-1
82 * for normal pair-list buffering, are passed separately, as in some cases
83 * we want an estimate for different values than the ones set in the inputrec.
84 * If reference_temperature < 0, the maximum coupling temperature will be used.
85 * The target is a maximum energy drift of ir->verletbuf_tol.
86 * Returns the number of non-linear virtual sites. For these it's difficult
87 * to determine their contribution to the drift exaclty, so we approximate.
88 * Returns the pair-list cut-off.
90 void calc_verlet_buffer_size(const gmx_mtop_t *mtop, real boxvol,
94 real reference_temperature,
95 const verletbuf_list_setup_t *list_setup,
99 /* Struct for unique atom type for calculating the energy drift.
100 * The atom displacement depends on mass and constraints.
101 * The energy jump for given distance depend on LJ type and q.
103 struct atom_nonbonded_kinetic_prop_t
105 real mass; /* mass */
106 int type; /* type (used for LJ parameters) */
108 gmx_bool bConstr; /* constrained, if TRUE, use #DOF=2 iso 3 */
109 real con_mass; /* mass of heaviest atom connected by constraints */
110 real con_len; /* constraint length to the heaviest atom */
113 /* This function computes two components of the estimate of the variance
114 * in the displacement of one atom in a system of two constrained atoms.
115 * Returns in sigma2_2d the variance due to rotation of the constrained
116 * atom around the atom to which it constrained.
117 * Returns in sigma2_3d the variance due to displacement of the COM
118 * of the whole system of the two constrained atoms.
120 * Only exposed here for testing purposes.
122 void constrained_atom_sigma2(real kT_fac,
123 const atom_nonbonded_kinetic_prop_t *prop,