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37 * Implements gmx::analysismodules::Freevolume.
39 * \author David van der Spoel <david.vanderspoel@icm.uu.se>
40 * \ingroup module_trajectoryanalysis
44 #include "freevolume.h"
48 #include "gromacs/analysisdata/analysisdata.h"
49 #include "gromacs/analysisdata/modules/average.h"
50 #include "gromacs/analysisdata/modules/plot.h"
51 #include "gromacs/fileio/trx.h"
52 #include "gromacs/legacyheaders/copyrite.h"
53 #include "gromacs/math/vec.h"
54 #include "gromacs/options/basicoptions.h"
55 #include "gromacs/options/filenameoption.h"
56 #include "gromacs/options/ioptionscontainer.h"
57 #include "gromacs/pbcutil/pbc.h"
58 #include "gromacs/random/random.h"
59 #include "gromacs/selection/nbsearch.h"
60 #include "gromacs/selection/selection.h"
61 #include "gromacs/selection/selectionoption.h"
62 #include "gromacs/topology/atomprop.h"
63 #include "gromacs/topology/topology.h"
64 #include "gromacs/trajectoryanalysis/analysissettings.h"
65 #include "gromacs/utility/arrayref.h"
66 #include "gromacs/utility/exceptions.h"
71 namespace analysismodules
78 * Class used to compute free volume in a simulations box.
80 * Inherits TrajectoryAnalysisModule and all functions from there.
81 * Does not implement any new functionality.
83 * \ingroup module_trajectoryanalysis
85 class FreeVolume : public TrajectoryAnalysisModule
89 virtual ~FreeVolume();
91 virtual void initOptions(IOptionsContainer *options,
92 TrajectoryAnalysisSettings *settings);
93 virtual void initAnalysis(const TrajectoryAnalysisSettings &settings,
94 const TopologyInformation &top);
95 virtual void analyzeFrame(int frnr, const t_trxframe &fr, t_pbc *pbc,
96 TrajectoryAnalysisModuleData *pdata);
97 virtual void finishAnalysis(int nframes);
98 virtual void writeOutput();
101 std::string fnFreevol_;
104 AnalysisDataAverageModulePointer adata_;
112 AnalysisNeighborhood nb_;
113 //! The van der Waals radius per atom
114 std::vector<double> vdw_radius_;
116 // Copy and assign disallowed by base.
119 // Constructor. Here it is important to initialize the pointer to
120 // subclasses that are elements of the main class. Here we have only
121 // one. The type of this depends on what kind of tool you need.
122 // Here we only have simple value/time kind of data.
123 FreeVolume::FreeVolume()
124 : TrajectoryAnalysisModule(FreeVolumeInfo::name, FreeVolumeInfo::shortDescription),
125 adata_(new AnalysisDataAverageModule())
127 // We only compute two numbers per frame
128 data_.setColumnCount(0, 2);
129 // Tell the analysis framework that this component exists
130 registerAnalysisDataset(&data_, "freevolume");
141 FreeVolume::~FreeVolume()
143 // Destroy C structures where there is no automatic memory release
144 // C++ takes care of memory in classes (hopefully)
147 gmx_rng_destroy(rng_);
153 FreeVolume::initOptions(IOptionsContainer *options,
154 TrajectoryAnalysisSettings *settings)
156 static const char *const desc[] = {
157 "[THISMODULE] calculates the free volume in a box as",
158 "a function of time. The free volume is",
159 "plotted as a fraction of the total volume.",
160 "The program tries to insert a probe with a given radius,",
161 "into the simulations box and if the distance between the",
162 "probe and any atom is less than the sums of the",
163 "van der Waals radii of both atoms, the position is",
164 "considered to be occupied, i.e. non-free. By using a",
165 "probe radius of 0, the true free volume is computed.",
166 "By using a larger radius, e.g. 0.14 nm, roughly corresponding",
167 "to a water molecule, the free volume for a hypothetical",
168 "particle with that size will be produced.",
169 "Note however, that since atoms are treated as hard-spheres",
170 "these number are very approximate, and typically only",
171 "relative changes are meaningful, for instance by doing a",
172 "series of simulations at different temperature.[PAR]",
173 "The group specified by the selection is considered to",
174 "delineate non-free volume.",
175 "The number of insertions per unit of volume is important",
176 "to get a converged result. About 1000/nm^3 yields an overall",
177 "standard deviation that is determined by the fluctuations in",
178 "the trajectory rather than by the fluctuations due to the",
179 "random numbers.[PAR]",
180 "The results are critically dependent on the van der Waals radii;",
181 "we recommend to use the values due to Bondi (1964).[PAR]",
182 "The Fractional Free Volume (FFV) that some authors like to use",
183 "is given by 1 - 1.3*(1-Free Volume). This value is printed on",
187 settings->setHelpText(desc);
189 // Add option for optional output file
190 options->addOption(FileNameOption("o").filetype(eftPlot).outputFile()
191 .store(&fnFreevol_).defaultBasename("freevolume")
192 .description("Computed free volume"));
194 // Add option for selecting a subset of atoms
195 options->addOption(SelectionOption("select")
196 .store(&sel_).defaultSelectionText("all")
198 .description("Atoms that are considered as part of the excluded volume"));
200 // Add option for the probe radius and initialize it
201 options->addOption(DoubleOption("radius").store(&probeRadius_)
202 .description("Radius of the probe to be inserted (nm, 0 yields the true free volume)"));
204 // Add option for the random number seed and initialize it to
205 // generate a value automatically
206 options->addOption(IntegerOption("seed").store(&seed_)
207 .description("Seed for random number generator."));
209 // Add option to determine number of insertion trials per frame
210 options->addOption(IntegerOption("ninsert").store(&ninsert_)
211 .description("Number of probe insertions per cubic nm to try for each frame in the trajectory."));
213 // Control input settings
214 settings->setFlags(TrajectoryAnalysisSettings::efRequireTop |
215 TrajectoryAnalysisSettings::efNoUserPBC);
216 settings->setPBC(true);
221 FreeVolume::initAnalysis(const TrajectoryAnalysisSettings &settings,
222 const TopologyInformation &top)
224 // Add the module that will contain the averaging and the time series
225 // for our calculation
226 data_.addModule(adata_);
228 // Add a module for plotting the data automatically at the end of
229 // the calculation. With this in place you only have to add data
230 // points to the data et.
231 AnalysisDataPlotModulePointer plotm_(new AnalysisDataPlotModule());
232 plotm_->setSettings(settings.plotSettings());
233 plotm_->setFileName(fnFreevol_);
234 plotm_->setTitle("Free Volume");
235 plotm_->setXAxisIsTime();
236 plotm_->setYLabel("Free Volume (%)");
237 plotm_->appendLegend("Free Volume");
238 plotm_->appendLegend("Volume");
240 data_.addModule(plotm_);
245 gmx_atomprop_t aps = gmx_atomprop_init();
246 t_atoms *atoms = &(top.topology()->atoms);
248 // Compute total mass
250 for (int i = 0; (i < atoms->nr); i++)
252 mtot_ += atoms->atom[i].m;
255 // Extracts number of molecules
256 nmol_ = top.topology()->mols.nr;
258 // Loop over atoms in the selection using an iterator
259 const int maxnovdw = 10;
260 ConstArrayRef<int> atomind = sel_.atomIndices();
261 for (ConstArrayRef<int>::iterator ai = atomind.begin(); (ai < atomind.end()); ++ai)
263 // Dereference the iterator to obtain an atom number
267 // Lookup the Van der Waals radius of this atom
268 int resnr = atoms->atom[i].resind;
269 if (TRUE == gmx_atomprop_query(aps, epropVDW,
270 *(atoms->resinfo[resnr].name),
271 *(atoms->atomname[i]),
274 vdw_radius_.push_back(value);
283 if (nnovdw < maxnovdw)
285 fprintf(stderr, "Could not determine VDW radius for %s-%s. Set to zero.\n",
286 *(atoms->resinfo[resnr].name),
287 *(atoms->atomname[i]));
289 vdw_radius_.push_back(0.0);
292 gmx_atomprop_destroy(aps);
294 // Increase cutoff by proberadius to make sure we do not miss
296 cutoff_ += probeRadius_;
298 if (nnovdw >= maxnovdw)
300 fprintf(stderr, "Could not determine VDW radius for %d particles. These were set to zero.\n", nnovdw);
303 // Print parameters to output. Maybe should make dependent on
305 printf("cutoff = %g nm\n", cutoff_);
306 printf("probe_radius = %g nm\n", probeRadius_);
307 printf("seed = %d\n", seed_);
308 printf("ninsert = %d probes per nm^3\n", ninsert_);
310 // Initiate the random number generator
311 rng_ = gmx_rng_init(seed_);
313 // Initiate the neighborsearching code
314 nb_.setCutoff(cutoff_);
318 FreeVolume::analyzeFrame(int frnr, const t_trxframe &fr, t_pbc *pbc,
319 TrajectoryAnalysisModuleData *pdata)
321 AnalysisDataHandle dh = pdata->dataHandle(data_);
322 const Selection &sel = pdata->parallelSelection(sel_);
324 GMX_RELEASE_ASSERT(NULL != pbc, "You have no periodic boundary conditions");
326 // Analysis framework magic
327 dh.startFrame(frnr, fr.time);
329 // Compute volume and number of insertions to perform
330 real V = det(fr.box);
331 int Ninsert = static_cast<int>(ninsert_*V);
333 // Use neighborsearching tools!
334 AnalysisNeighborhoodSearch nbsearch = nb_.initSearch(pbc, sel);
336 // Then loop over insertions
338 for (int i = 0; (i < Ninsert); i++)
342 for (int m = 0; (m < DIM); m++)
344 // Generate random number between 0 and 1
345 rand[m] = gmx_rng_uniform_real(rng_);
347 // Generate random 3D position within the box
348 mvmul(fr.box, rand, ins);
350 // Find the first reference position within the cutoff.
351 bool bOverlap = false;
352 AnalysisNeighborhoodPair pair;
353 AnalysisNeighborhoodPairSearch pairSearch = nbsearch.startPairSearch(ins);
354 while (!bOverlap && pairSearch.findNextPair(&pair))
356 int jp = pair.refIndex();
357 // Compute distance vector to first atom in the neighborlist
358 pbc_dx(pbc, ins, sel.position(jp).x(), dx);
360 // See whether the distance is smaller than allowed
361 bOverlap = (norm(dx) <
362 probeRadius_+vdw_radius_[sel.position(jp).refId()]);
368 // We found some free volume!
372 // Compute total free volume for this frame
376 frac = (100.0*NinsTot)/Ninsert;
378 // Add the free volume fraction to the data set in column 0
379 dh.setPoint(0, frac);
380 // Add the total volume to the data set in column 1
389 FreeVolume::finishAnalysis(int /* nframes */)
391 please_cite(stdout, "Bondi1964a");
392 please_cite(stdout, "Lourenco2013a");
396 FreeVolume::writeOutput()
398 // Final results come from statistics module in analysis framework
399 double FVaver = adata_->average(0, 0);
400 double FVerror = adata_->standardDeviation(0, 0);
401 printf("Free volume %.2f +/- %.2f %%\n", FVaver, FVerror);
403 double Vaver = adata_->average(0, 1);
404 double Verror = adata_->standardDeviation(0, 1);
405 printf("Total volume %.2f +/- %.2f nm^3\n", Vaver, Verror);
407 printf("Number of molecules %d total mass %.2f Dalton\n", nmol_, mtot_);
408 double RhoAver = mtot_ / (Vaver * 1e-24 * AVOGADRO);
409 double RhoError = sqr(RhoAver / Vaver)*Verror;
410 printf("Average molar mass: %.2f Dalton\n", mtot_/nmol_);
412 double VmAver = Vaver/nmol_;
413 double VmError = Verror/nmol_;
414 printf("Density rho: %.2f +/- %.2f nm^3\n", RhoAver, RhoError);
415 printf("Molecular volume Vm assuming homogeneity: %.4f +/- %.4f nm^3\n",
418 double VvdWaver = (1-FVaver/100)*VmAver;
419 double VvdWerror = 0;
420 printf("Molecular van der Waals volume assuming homogeneity: %.4f +/- %.4f nm^3\n",
421 VvdWaver, VvdWerror);
423 double FFVaver = 1-1.3*((100-FVaver)/100);
424 double FFVerror = (FVerror/FVaver)*FFVaver;
425 printf("Fractional free volume %.3f +/- %.3f\n", FFVaver, FFVerror);
430 const char FreeVolumeInfo::name[] = "freevolume";
431 const char FreeVolumeInfo::shortDescription[] =
432 "Calculate free volume";
434 TrajectoryAnalysisModulePointer FreeVolumeInfo::create()
436 return TrajectoryAnalysisModulePointer(new FreeVolume);
439 } // namespace analysismodules