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44 #include "gromacs/commandline/pargs.h"
45 #include "gromacs/commandline/viewit.h"
46 #include "gromacs/fileio/trxio.h"
47 #include "gromacs/fileio/xvgr.h"
48 #include "gromacs/gmxana/gmx_ana.h"
49 #include "gromacs/gmxana/princ.h"
50 #include "gromacs/math/functions.h"
51 #include "gromacs/math/utilities.h"
52 #include "gromacs/math/vec.h"
53 #include "gromacs/pbcutil/rmpbc.h"
54 #include "gromacs/topology/index.h"
55 #include "gromacs/topology/topology.h"
56 #include "gromacs/utility/arraysize.h"
57 #include "gromacs/utility/cstringutil.h"
58 #include "gromacs/utility/fatalerror.h"
59 #include "gromacs/utility/futil.h"
60 #include "gromacs/utility/smalloc.h"
62 #define EPS0 8.85419E-12
63 #define ELC 1.60219E-19
65 /****************************************************************************/
66 /* This program calculates the electrostatic potential across the box by */
67 /* determining the charge density in slices of the box and integrating these*/
69 /* Peter Tieleman, April 1995 */
70 /* It now also calculates electrostatic potential in spherical micelles, */
71 /* using \frac{1}{r}\frac{d^2r\Psi}{r^2} = - \frac{\rho}{\epsilon_0} */
72 /* This probably sucks but it seems to work. */
73 /****************************************************************************/
75 static int ce = 0, cb = 0;
77 /* this routine integrates the array data and returns the resulting array */
78 /* routine uses simple trapezoid rule */
79 static void p_integrate(double* result, const double data[], int ndata, double slWidth)
87 "Warning: nr of slices very small. This will result"
91 fprintf(stderr, "Integrating from slice %d to slice %d\n", cb, ndata - ce);
93 for (slice = cb; slice < (ndata - ce); slice++)
96 for (i = cb; i < slice; i++)
98 sum += slWidth * (data[i] + 0.5 * (data[i + 1] - data[i]));
104 static void calc_potential(const char* fn,
107 double*** slPotential,
111 const t_topology* top,
119 const gmx_output_env_t* oenv)
121 rvec* x0; /* coordinates without pbc */
122 matrix box; /* box (3x3) */
123 int natoms; /* nr. atoms in trj */
125 int i, n, /* loop indices */
126 teller = 0, ax1 = 0, ax2 = 0, nr_frames = 0, /* number of frames */
127 slice; /* current slice */
128 double slVolume; /* volume of slice for spherical averaging */
133 gmx_rmpbc_t gpbc = nullptr;
149 default: gmx_fatal(FARGS, "Invalid axes. Terminating\n");
152 if ((natoms = read_first_x(oenv, &status, fn, &t, &x0, box)) == 0)
154 gmx_fatal(FARGS, "Could not read coordinates from statusfile\n");
159 *nslices = static_cast<int>(box[axis][axis] * 10.0); /* default value */
161 fprintf(stderr, "\nDividing the box in %d slices\n", *nslices);
163 snew(*slField, nr_grps);
164 snew(*slCharge, nr_grps);
165 snew(*slPotential, nr_grps);
167 for (i = 0; i < nr_grps; i++)
169 snew((*slField)[i], *nslices);
170 snew((*slCharge)[i], *nslices);
171 snew((*slPotential)[i], *nslices);
175 gpbc = gmx_rmpbc_init(&top->idef, pbcType, natoms);
177 /*********** Start processing trajectory ***********/
180 *slWidth = box[axis][axis] / static_cast<real>((*nslices));
182 gmx_rmpbc(gpbc, natoms, box, x0);
184 /* calculate position of center of mass based on group 1 */
185 calc_xcm(x0, gnx[0], index[0], top->atoms.atom, xcm, FALSE);
188 for (n = 0; n < nr_grps; n++)
190 /* Check whether we actually have all positions of the requested index
191 * group in the trajectory file */
195 "You selected a group with %d atoms, but only %d atoms\n"
196 "were found in the trajectory.\n",
200 for (i = 0; i < gnx[n]; i++) /* loop over all atoms in index file */
204 rvec_add(x0[index[n][i]], xcm, x0[index[n][i]]);
205 /* only distance from origin counts, not sign */
206 slice = static_cast<int>(norm(x0[index[n][i]]) / (*slWidth));
208 /* this is a nice check for spherical groups but not for
209 all water in a cubic box since a lot will fall outside
211 if (slice > (*nslices))
213 fprintf(stderr,"Warning: slice = %d\n",slice);
216 (*slCharge)[n][slice] += top->atoms.atom[index[n][i]].q;
220 z = x0[index[n][i]][axis];
224 z += box[axis][axis];
226 if (z > box[axis][axis])
228 z -= box[axis][axis];
230 /* determine which slice atom is in */
231 slice = static_cast<int>((z / (*slWidth)));
232 (*slCharge)[n][slice] += top->atoms.atom[index[n][i]].q;
237 } while (read_next_x(oenv, status, &t, x0, box));
239 gmx_rmpbc_done(gpbc);
241 /*********** done with status file **********/
244 /* slCharge now contains the total charge per slice, summed over all
245 frames. Now divide by nr_frames and integrate twice
252 "\n\nRead %d frames from trajectory. Calculating potential"
253 "in spherical coordinates\n",
258 fprintf(stderr, "\n\nRead %d frames from trajectory. Calculating potential\n", nr_frames);
261 for (n = 0; n < nr_grps; n++)
263 for (i = 0; i < *nslices; i++)
267 /* charge per volume is now the summed charge, divided by the nr
268 of frames and by the volume of the slice it's in, 4pi r^2 dr
270 slVolume = 4 * M_PI * gmx::square(i) * gmx::square(*slWidth) * *slWidth;
273 (*slCharge)[n][i] = 0;
277 (*slCharge)[n][i] = (*slCharge)[n][i] / (nr_frames * slVolume);
282 /* get charge per volume */
283 (*slCharge)[n][i] = (*slCharge)[n][i] * (*nslices)
284 / (static_cast<real>(nr_frames) * box[axis][axis]
285 * box[ax1][ax1] * box[ax2][ax2]);
288 /* Now we have charge densities */
291 if (bCorrect && !bSpherical)
293 for (n = 0; n < nr_grps; n++)
297 for (i = 0; i < *nslices; i++)
299 if (std::abs((*slCharge)[n][i]) >= GMX_DOUBLE_MIN)
302 qsum += (*slCharge)[n][i];
306 for (i = 0; i < *nslices; i++)
308 if (std::abs((*slCharge)[n][i]) >= GMX_DOUBLE_MIN)
310 (*slCharge)[n][i] -= qsum;
316 for (n = 0; n < nr_grps; n++)
318 /* integrate twice to get field and potential */
319 p_integrate((*slField)[n], (*slCharge)[n], *nslices, *slWidth);
323 if (bCorrect && !bSpherical)
325 for (n = 0; n < nr_grps; n++)
329 for (i = 0; i < *nslices; i++)
331 if (std::abs((*slCharge)[n][i]) >= GMX_DOUBLE_MIN)
334 qsum += (*slField)[n][i];
338 for (i = 0; i < *nslices; i++)
340 if (std::abs((*slCharge)[n][i]) >= GMX_DOUBLE_MIN)
342 (*slField)[n][i] -= qsum;
348 for (n = 0; n < nr_grps; n++)
350 p_integrate((*slPotential)[n], (*slField)[n], *nslices, *slWidth);
353 /* Now correct for eps0 and in spherical case for r*/
354 for (n = 0; n < nr_grps; n++)
356 for (i = 0; i < *nslices; i++)
360 (*slPotential)[n][i] = ELC * (*slPotential)[n][i] * -1.0E9 / (EPS0 * i * (*slWidth));
361 (*slField)[n][i] = ELC * (*slField)[n][i] * 1E18 / (EPS0 * i * (*slWidth));
365 (*slPotential)[n][i] = ELC * (*slPotential)[n][i] * -1.0E9 / EPS0;
366 (*slField)[n][i] = ELC * (*slField)[n][i] * 1E18 / EPS0;
371 sfree(x0); /* free memory used by coordinate array */
374 static void plot_potential(double* potential[],
382 const char* const grpname[],
384 const gmx_output_env_t* oenv)
386 FILE *pot, /* xvgr file with potential */
387 *cha, /* xvgr file with charges */
388 *fie; /* xvgr files with fields */
389 char buf[256]; /* for xvgr title */
392 sprintf(buf, "Electrostatic Potential");
393 pot = xvgropen(afile, buf, "Box (nm)", "Potential (V)", oenv);
394 xvgr_legend(pot, nr_grps, grpname, oenv);
396 sprintf(buf, "Charge Distribution");
397 cha = xvgropen(bfile, buf, "Box (nm)", "Charge density (q/nm\\S3\\N)", oenv);
398 xvgr_legend(cha, nr_grps, grpname, oenv);
400 sprintf(buf, "Electric Field");
401 fie = xvgropen(cfile, buf, "Box (nm)", "Field (V/nm)", oenv);
402 xvgr_legend(fie, nr_grps, grpname, oenv);
404 for (slice = cb; slice < (nslices - ce); slice++)
406 fprintf(pot, "%20.16g ", slice * slWidth);
407 fprintf(cha, "%20.16g ", slice * slWidth);
408 fprintf(fie, "%20.16g ", slice * slWidth);
409 for (n = 0; n < nr_grps; n++)
411 fprintf(pot, " %20.16g", potential[n][slice]);
412 fprintf(fie, " %20.16g", field[n][slice] / 1e9); /* convert to V/nm */
413 fprintf(cha, " %20.16g", charge[n][slice]);
425 int gmx_potential(int argc, char* argv[])
427 const char* desc[] = {
428 "[THISMODULE] computes the electrostatical potential across the box. The potential is",
429 "calculated by first summing the charges per slice and then integrating",
430 "twice of this charge distribution. Periodic boundaries are not taken",
431 "into account. Reference of potential is taken to be the left side of",
432 "the box. It is also possible to calculate the potential in spherical",
433 "coordinates as function of r by calculating a charge distribution in",
434 "spherical slices and twice integrating them. epsilon_r is taken as 1,",
435 "but 2 is more appropriate in many cases."
437 gmx_output_env_t* oenv;
438 static int axis = 2; /* normal to memb. default z */
439 static const char* axtitle = "Z";
440 static int nslices = 10; /* nr of slices defined */
441 static int ngrps = 1;
442 static gmx_bool bSpherical = FALSE; /* default is bilayer types */
443 static real fudge_z = 0; /* translate coordinates */
444 static gmx_bool bCorrect = false;
450 "Take the normal on the membrane in direction X, Y or Z." },
455 "Calculate potential as function of boxlength, dividing the box"
456 " in this number of slices." },
461 "Discard this number of first slices of box for integration" },
466 "Discard this number of last slices of box for integration" },
471 "Translate all coordinates by this distance in the direction of the box" },
472 { "-spherical", FALSE, etBOOL, { &bSpherical }, "Calculate in spherical coordinates" },
473 { "-ng", FALSE, etINT, { &ngrps }, "Number of groups to consider" },
478 "Assume net zero charge of groups to improve accuracy" }
480 const char* bugs[] = { "Discarding slices for integration should not be necessary." };
482 double **potential, /* potential per slice */
483 **charge, /* total charge per slice */
484 **field, /* field per slice */
485 slWidth; /* width of one slice */
486 char** grpname; /* groupnames */
487 int* ngx; /* sizes of groups */
488 t_topology* top; /* topology */
490 int** index; /* indices for all groups */
492 /* files for g_order */
493 { efTRX, "-f", nullptr, ffREAD }, /* trajectory file */
494 { efNDX, nullptr, nullptr, ffREAD }, /* index file */
495 { efTPR, nullptr, nullptr, ffREAD }, /* topology file */
496 { efXVG, "-o", "potential", ffWRITE }, /* xvgr output file */
497 { efXVG, "-oc", "charge", ffWRITE }, /* xvgr output file */
498 { efXVG, "-of", "field", ffWRITE }, /* xvgr output file */
501 #define NFILE asize(fnm)
503 if (!parse_common_args(
504 &argc, argv, PCA_CAN_VIEW | PCA_CAN_TIME, NFILE, fnm, asize(pa), pa, asize(desc), desc, asize(bugs), bugs, &oenv))
510 axis = toupper(axtitle[0]) - 'X';
512 top = read_top(ftp2fn(efTPR, NFILE, fnm), &pbcType); /* read topology file */
514 snew(grpname, ngrps);
518 rd_index(ftp2fn(efNDX, NFILE, fnm), ngrps, ngx, index, grpname);
521 calc_potential(ftp2fn(efTRX, NFILE, fnm),
538 plot_potential(potential,
541 opt2fn("-o", NFILE, fnm),
542 opt2fn("-oc", NFILE, fnm),
543 opt2fn("-of", NFILE, fnm),
550 do_view(oenv, opt2fn("-o", NFILE, fnm), nullptr); /* view xvgr file */
551 do_view(oenv, opt2fn("-oc", NFILE, fnm), nullptr); /* view xvgr file */
552 do_view(oenv, opt2fn("-of", NFILE, fnm), nullptr); /* view xvgr file */