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47 #include "gmx_fatal.h"
62 int gmx_nmtraj(int argc, char *argv[])
66 "[TT]g_nmtraj[tt] generates an virtual trajectory from an eigenvector, ",
67 "corresponding to a harmonic Cartesian oscillation around the average ",
68 "structure. The eigenvectors should normally be mass-weighted, but you can ",
69 "use non-weighted eigenvectors to generate orthogonal motions. ",
70 "The output frames are written as a trajectory file covering an entire period, and ",
71 "the first frame is the average structure. If you write the trajectory in (or convert to) ",
72 "PDB format you can view it directly in PyMol and also render a photorealistic movie. ",
73 "Motion amplitudes are calculated from the eigenvalues and a preset temperature, ",
74 "assuming equipartition of the energy over all modes. To make the motion clearly visible ",
75 "in PyMol you might want to amplify it by setting an unrealistically high temperature. ",
76 "However, be aware that both the linear Cartesian displacements and mass weighting will ",
77 "lead to serious structure deformation for high amplitudes - this is is simply a limitation ",
78 "of the Cartesian normal mode model. By default the selected eigenvector is set to 7, since ",
79 " the first six normal modes are the translational and rotational degrees of freedom."
82 static real refamplitude = 0.25;
83 static int nframes = 30;
84 static real temp = 300.0;
85 static const char *eignrvec = "7";
86 static const char *phasevec = "0.0";
90 { "-eignr", FALSE, etSTR, {&eignrvec}, "String of eigenvectors to use (first is 1)" },
91 { "-phases", FALSE, etSTR, {&phasevec}, "String of phases (default is 0.0)" },
92 { "-temp", FALSE, etREAL, {&temp}, "Temperature (K)" },
93 { "-amplitude", FALSE, etREAL, {&refamplitude}, "Amplitude for modes with eigenvalue<=0" },
94 { "-nframes", FALSE, etINT, {&nframes}, "Number of frames to generate" }
103 rvec *xtop, *xref, *xav, *xout;
104 int nvec, *eignr = NULL;
106 rvec **eigvec = NULL;
109 int i, j, k, kmode, d, s, v;
110 gmx_bool bDMR, bDMA, bFit;
123 real omega, Ekin, sum, m, vel;
136 { efTPS, NULL, NULL, ffREAD },
137 { efTRN, "-v", "eigenvec", ffREAD },
138 { efTRO, "-o", "nmtraj", ffWRITE }
141 #define NFILE asize(fnm)
143 parse_common_args(&argc, argv, PCA_BE_NICE,
144 NFILE, fnm, NPA, pa, asize(desc), desc, 0, NULL, &oenv);
146 read_eigenvectors(opt2fn("-v", NFILE, fnm), &natoms, &bFit,
147 &xref, &bDMR, &xav, &bDMA, &nvec, &eignr, &eigvec, &eigval);
149 read_tps_conf(ftp2fn(efTPS, NFILE, fnm), title, &top, &ePBC, &xtop, NULL, box, bDMA);
151 /* Find vectors and phases */
153 /* first find number of args in string */
158 dum = strtod(p, &pe);
163 snew(imodes, nmodes);
165 for (i = 0; i < nmodes; i++)
167 /* C indices start on 0 */
168 imodes[i] = strtol(p, &pe, 10)-1;
172 /* Now read phases */
177 dum = strtod(p, &pe);
181 if (nphases > nmodes)
183 gmx_fatal(FARGS, "More phases than eigenvector indices specified.\n");
186 snew(phases, nmodes);
189 for (i = 0; i < nphases; i++)
191 phases[i] = strtod(p, &pe);
195 if (nmodes > nphases)
197 printf("Warning: Setting phase of last %d modes to zero...\n", nmodes-nphases);
200 for (i = nphases; i < nmodes; i++)
207 if (atoms->nr != natoms)
209 gmx_fatal(FARGS, "Different number of atoms in topology and eigenvectors.\n");
213 for (i = 0; i < natoms; i++)
218 /* Find the eigenvalue/vector to match our select one */
219 snew(out_eigidx, nmodes);
220 for (i = 0; i < nmodes; i++)
225 for (i = 0; i < nvec; i++)
227 for (j = 0; j < nmodes; j++)
229 if (imodes[j] == eignr[i])
235 for (i = 0; i < nmodes; i++)
237 if (out_eigidx[i] == -1)
239 gmx_fatal(FARGS, "Could not find mode %d in eigenvector file.\n", imodes[i]);
244 snew(invsqrtm, natoms);
248 for (i = 0; (i < natoms); i++)
250 invsqrtm[i] = gmx_invsqrt(atoms->atom[i].m);
255 for (i = 0; (i < natoms); i++)
262 snew(amplitude, nmodes);
264 printf("mode phases: %g %g\n", phases[0], phases[1]);
266 for (i = 0; i < nmodes; i++)
268 kmode = out_eigidx[i];
269 this_eigvec = eigvec[kmode];
271 if ( (kmode >= 6) && (eigval[kmode] > 0))
273 /* Derive amplitude from temperature and eigenvalue if we can */
275 /* Convert eigenvalue to angular frequency, in units s^(-1) */
276 omega = sqrt(eigval[kmode]*1.0E21/(AVOGADRO*AMU));
277 /* Harmonic motion will be x=x0 + A*sin(omega*t)*eigenvec.
278 * The velocity is thus:
280 * v = A*omega*cos(omega*t)*eigenvec.
282 * And the average kinetic energy the integral of mass*v*v/2 over a
285 * (1/4)*mass*A*omega*eigenvec
287 * For t =2*pi*n, all energy will be kinetic, and v=A*omega*eigenvec.
288 * The kinetic energy will be sum(0.5*mass*v*v) if we temporarily set A to 1,
289 * and the average over a period half of this.
293 for (k = 0; k < natoms; k++)
295 m = atoms->atom[k].m;
296 for (d = 0; d < DIM; d++)
298 vel = omega*this_eigvec[k][d];
299 Ekin += 0.5*0.5*m*vel*vel;
303 /* Convert Ekin from amu*(nm/s)^2 to J, i.e., kg*(m/s)^2
304 * This will also be proportional to A^2
308 /* Set the amplitude so the energy is kT/2 */
309 amplitude[i] = sqrt(0.5*BOLTZMANN*temp/Ekin);
313 amplitude[i] = refamplitude;
317 out = open_trx(ftp2fn(efTRO, NFILE, fnm), "w");
319 /* Write a sine oscillation around the average structure,
320 * modulated by the eigenvector with selected amplitude.
323 for (i = 0; i < nframes; i++)
325 fraction = (real)i/(real)nframes;
326 for (j = 0; j < natoms; j++)
328 copy_rvec(xav[j], xout[j]);
331 for (k = 0; k < nmodes; k++)
333 kmode = out_eigidx[k];
334 this_eigvec = eigvec[kmode];
336 for (j = 0; j < natoms; j++)
338 for (d = 0; d < DIM; d++)
340 xout[j][d] += amplitude[k]*sin(2*M_PI*(fraction+phases[k]/360.0))*this_eigvec[j][d];
344 write_trx(out, natoms, dummy, atoms, i, (real)i/(real)nframes, box, xout, NULL, NULL);
347 fprintf(stderr, "\n");