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45 #include "gromacs/utility/smalloc.h"
46 #include "gromacs/utility/futil.h"
47 #include "gromacs/commandline/pargs.h"
50 #include "gromacs/utility/fatalerror.h"
52 #include "gromacs/math/vec.h"
55 #include "gromacs/fileio/trxio.h"
58 int gmx_rotacf(int argc, char *argv[])
60 const char *desc[] = {
61 "[THISMODULE] calculates the rotational correlation function",
62 "for molecules. Atom triplets (i,j,k) must be given in the index",
63 "file, defining two vectors ij and jk. The rotational ACF",
64 "is calculated as the autocorrelation function of the vector",
65 "n = ij x jk, i.e. the cross product of the two vectors.",
66 "Since three atoms span a plane, the order of the three atoms",
67 "does not matter. Optionally, by invoking the [TT]-d[tt] switch, you can",
68 "calculate the rotational correlation function for linear molecules",
69 "by specifying atom pairs (i,j) in the index file.",
72 "[TT]gmx rotacf -P 1 -nparm 2 -fft -n index -o rotacf-x-P1",
73 "-fa expfit-x-P1 -beginfit 2.5 -endfit 20.0[tt][PAR]",
74 "This will calculate the rotational correlation function using a first",
75 "order Legendre polynomial of the angle of a vector defined by the index",
76 "file. The correlation function will be fitted from 2.5 ps until 20.0 ps",
77 "to a two-parameter exponential."
79 static gmx_bool bVec = FALSE, bAver = TRUE;
82 { "-d", FALSE, etBOOL, {&bVec},
83 "Use index doublets (vectors) for correlation function instead of triplets (planes)" },
84 { "-aver", FALSE, etBOOL, {&bAver},
85 "Average over molecules" }
96 int i, m, teller, n_alloc, natoms, nvec, ai, aj, ak;
99 gmx_rmpbc_t gpbc = NULL;
103 { efTRX, "-f", NULL, ffREAD },
104 { efTPX, NULL, NULL, ffREAD },
105 { efNDX, NULL, NULL, ffREAD },
106 { efXVG, "-o", "rotacf", ffWRITE }
108 #define NFILE asize(fnm)
115 ppa = add_acf_pargs(&npargs, pa);
117 if (!parse_common_args(&argc, argv, PCA_CAN_VIEW | PCA_CAN_TIME | PCA_BE_NICE,
118 NFILE, fnm, npargs, ppa, asize(desc), desc, 0, NULL, &oenv))
123 rd_index(ftp2fn(efNDX, NFILE, fnm), 1, &isize, &index, &grpname);
134 if (((isize % 3) != 0) && !bVec)
136 gmx_fatal(FARGS, "number of index elements not multiple of 3, "
137 "these can not be atom triplets\n");
139 if (((isize % 2) != 0) && bVec)
141 gmx_fatal(FARGS, "number of index elements not multiple of 2, "
142 "these can not be atom doublets\n");
145 top = read_top(ftp2fn(efTPX, NFILE, fnm), &ePBC);
148 for (i = 0; (i < nvec); i++)
154 natoms = read_first_x(oenv, &status, ftp2fn(efTRX, NFILE, fnm), &t, &x, box);
157 gpbc = gmx_rmpbc_init(&(top->idef), ePBC, natoms);
159 /* Start the loop over frames */
164 if (teller >= n_alloc)
167 for (i = 0; (i < nvec); i++)
169 srenew(c1[i], DIM*n_alloc);
174 /* Remove periodicity */
175 gmx_rmpbc_copy(gpbc, natoms, box, x, x_s);
177 /* Compute crossproducts for all vectors, if triplets.
178 * else, just get the vectors in case of doublets.
182 for (i = 0; (i < nvec); i++)
187 rvec_sub(x_s[ai], x_s[aj], xij);
188 rvec_sub(x_s[aj], x_s[ak], xjk);
190 for (m = 0; (m < DIM); m++)
192 c1[i][DIM*teller+m] = n[m];
198 for (i = 0; (i < nvec); i++)
202 rvec_sub(x_s[ai], x_s[aj], n);
203 for (m = 0; (m < DIM); m++)
205 c1[i][DIM*teller+m] = n[m];
209 /* Increment loop counter */
212 while (read_next_x(oenv, status, &t, x, box));
214 fprintf(stderr, "\nDone with trajectory\n");
216 gmx_rmpbc_done(gpbc);
219 /* Autocorrelation function */
222 fprintf(stderr, "Not enough frames for correlation function\n");
226 dt = (t1 - t0)/(teller-1);
230 do_autocorr(ftp2fn(efXVG, NFILE, fnm), oenv, "Rotational Correlation Function",
231 teller, nvec, c1, dt, mode, bAver);
234 do_view(oenv, ftp2fn(efXVG, NFILE, fnm), NULL);