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37 * Implements nblib utility functions
39 * \author Victor Holanda <victor.holanda@cscs.ch>
40 * \author Joe Jordan <ejjordan@kth.se>
41 * \author Prashanth Kanduri <kanduri@cscs.ch>
42 * \author Sebastian Keller <keller@cscs.ch>
43 * \author Artem Zhmurov <zhmurov@gmail.com>
46 #include "nblib/util/user.h"
47 #include "gromacs/random/tabulatednormaldistribution.h"
48 #include "gromacs/random/threefry.h"
49 #include "gromacs/utility/fatalerror.h"
57 std::string next_token(std::string& s, const std::string& delimiter)
59 std::string token = s.substr(0, s.find(delimiter));
61 std::size_t next = s.find(delimiter);
62 if (next == std::string::npos)
65 s.erase(0, next + delimiter.length());
72 //! Generates an array of particle velocities based on the Maxwell-Boltzmann distribution
73 //! using temperature, masses and a random number generator
74 static std::vector<Vec3> low_mspeed(real tempi, std::vector<real> const& masses, gmx::ThreeFry2x64<>* rng)
79 gmx::TabulatedNormalDistribution<real> normalDist;
81 std::vector<Vec3> velocities(masses.size());
83 boltz = BOLTZ * tempi;
86 for (size_t i = 0; i < masses.size(); i++)
88 real mass = masses[i];
92 real sd = std::sqrt(boltz / mass);
93 for (int m = 0; (m < dimSize); m++)
95 velocities[i][m] = sd * normalDist(*rng);
96 ekin += 0.5 * mass * velocities[i][m] * velocities[i][m];
101 temp = (2.0 * ekin) / (nrdf * BOLTZ);
104 real scal = std::sqrt(tempi / temp);
105 for (auto& vel : velocities)
107 for (int m = 0; (m < dimSize); m++)
113 fprintf(stderr, "Velocities were taken from a Maxwell distribution at %g K\n", tempi);
117 "Velocities were taken from a Maxwell distribution\n"
118 "Initial generated temperature: %12.5e (scaled to: %12.5e)\n",
125 //! Generate velocities from a Maxwell Boltzmann distribution, masses should be the
126 //! same as the ones specified for the Topology object
127 std::vector<Vec3> generateVelocity(real tempi, unsigned int seed, std::vector<real> const& masses)
132 seed = static_cast<int>(gmx::makeRandomSeed());
133 fprintf(stderr, "Using random seed %u for generating velocities\n", seed);
135 gmx::ThreeFry2x64<> rng(seed, gmx::RandomDomain::MaxwellVelocities);
137 return low_mspeed(tempi, masses, &rng);
140 //! Check within the container of gmx::RVecs for a NaN or inf
141 bool checkNumericValues(const std::vector<Vec3>& values)
143 for (auto val : values)
145 for (int m = 0; (m < dimSize); m++)
147 if (std::isnan(val[m]) or std::isinf(val[m]))