Esempio n. 1
0
static void dump_fy(output_env_t oenv, real toler)
{
    FILE       *fp;
    double      Delta, f, y, DD;
    const char *leg[] = { "f", "fy", "y" };

    DD = pow(10.0, 0.125);
    fp = xvgropen("fy.xvg", "Fig. 2, Lin2003a", "Delta", "y or fy", oenv);
    xvgr_legend(fp, asize(leg), leg, oenv);
    fprintf(fp, "@    world 1e-05, 0, 1000, 1\n");
    fprintf(fp, "@    xaxes scale Logarithmic\n");
    for (Delta = 1e-5; (Delta <= 1000); Delta *= DD)
    {
        f = calc_fluidicity(Delta, toler);
        y = calc_y(f, Delta, toler);
        fprintf(fp, "%10g  %10g  %10g  %10g\n", Delta, f, f*y, y);
    }
    xvgrclose(fp);
}
Esempio n. 2
0
int gmx_dos(int argc, char *argv[])
{
    const char         *desc[] = {
        "[TT]g_dos[tt] computes the Density of States from a simulations.",
        "In order for this to be meaningful the velocities must be saved",
        "in the trajecotry with sufficiently high frequency such as to cover",
        "all vibrations. For flexible systems that would be around a few fs",
        "between saving. Properties based on the DoS are printed on the",
        "standard output."
    };
    const char         *bugs[] = {
        "This program needs a lot of memory: total usage equals the number of atoms times 3 times number of frames times 4 (or 8 when run in double precision)."
    };
    FILE               *fp, *fplog;
    t_topology          top;
    int                 ePBC = -1;
    t_trxframe          fr;
    matrix              box;
    int                 gnx;
    char                title[256];
    real                t0, t1, m;
    t_trxstatus        *status;
    int                 nV, nframes, n_alloc, i, j, k, l, fftcode, Nmol, Natom;
    double              rho, dt, V2sum, Vsum, V, tmass, dostot, dos2, dosabs;
    real              **c1, **dos, mi, beta, bfac, *nu, *tt, stddev, c1j;
    output_env_t        oenv;
    gmx_fft_t           fft;
    double              cP, S, A, E, DiffCoeff, Delta, f, y, z, sigHS, Shs, Sig, DoS0, recip_fac;
    double              wCdiff, wSdiff, wAdiff, wEdiff;

    static     gmx_bool bVerbose = TRUE, bAbsolute = FALSE, bNormalize = FALSE;
    static     gmx_bool bRecip   = FALSE, bDump = FALSE;
    static     real     Temp     = 298.15, toler = 1e-6;
    t_pargs             pa[]     = {
        { "-v", FALSE, etBOOL, {&bVerbose},
          "Be loud and noisy." },
        { "-recip", FALSE, etBOOL, {&bRecip},
          "Use cm^-1 on X-axis instead of 1/ps for DoS plots." },
        { "-abs", FALSE, etBOOL, {&bAbsolute},
          "Use the absolute value of the Fourier transform of the VACF as the Density of States. Default is to use the real component only" },
        { "-normdos", FALSE, etBOOL, {&bNormalize},
          "Normalize the DoS such that it adds up to 3N. This is a hack that should not be necessary." },
        { "-T", FALSE, etREAL, {&Temp},
          "Temperature in the simulation" },
        { "-toler", FALSE, etREAL, {&toler},
          "[HIDDEN]Tolerance when computing the fluidicity using bisection algorithm" },
        { "-dump", FALSE, etBOOL, {&bDump},
          "[HIDDEN]Dump the y/fy plot corresponding to Fig. 2 inLin2003a and the and the weighting functions corresponding to Fig. 1 in Berens1983a." }
    };

    t_filenm            fnm[] = {
        { efTRN, "-f",    NULL,    ffREAD  },
        { efTPX, "-s",    NULL,    ffREAD  },
        { efNDX, NULL,    NULL,    ffOPTRD },
        { efXVG, "-vacf", "vacf",  ffWRITE },
        { efXVG, "-mvacf", "mvacf", ffWRITE },
        { efXVG, "-dos",  "dos",   ffWRITE },
        { efLOG, "-g",    "dos",   ffWRITE },
    };
#define NFILE asize(fnm)
    int                 npargs;
    t_pargs            *ppa;
    const char         *DoSlegend[] = {
        "DoS(v)", "DoS(v)[Solid]", "DoS(v)[Diff]"
    };

    npargs = asize(pa);
    ppa    = add_acf_pargs(&npargs, pa);
    parse_common_args(&argc, argv, PCA_CAN_VIEW | PCA_CAN_TIME | PCA_BE_NICE,
                      NFILE, fnm, npargs, ppa, asize(desc), desc,
                      asize(bugs), bugs, &oenv);

    beta = 1/(Temp*BOLTZ);
    if (bDump)
    {
        printf("Dumping reference figures. Thanks for your patience.\n");
        dump_fy(oenv, toler);
        dump_w(oenv, beta);
        exit(0);
    }

    fplog = gmx_fio_fopen(ftp2fn(efLOG, NFILE, fnm), "w");
    fprintf(fplog, "Doing density of states analysis based on trajectory.\n");
    please_cite(fplog, "Pascal2011a");
    please_cite(fplog, "Caleman2011b");

    read_tps_conf(ftp2fn(efTPX, NFILE, fnm), title, &top, &ePBC, NULL, NULL, box,
                  TRUE);
    V     = det(box);
    tmass = 0;
    for (i = 0; (i < top.atoms.nr); i++)
    {
        tmass += top.atoms.atom[i].m;
    }

    Natom = top.atoms.nr;
    Nmol  = top.mols.nr;
    gnx   = Natom*DIM;

    /* Correlation stuff */
    snew(c1, gnx);
    for (i = 0; (i < gnx); i++)
    {
        c1[i] = NULL;
    }

    read_first_frame(oenv, &status, ftp2fn(efTRN, NFILE, fnm), &fr, TRX_NEED_V);
    t0 = fr.time;

    n_alloc = 0;
    nframes = 0;
    Vsum    = V2sum = 0;
    nV      = 0;
    do
    {
        if (fr.bBox)
        {
            V      = det(fr.box);
            V2sum += V*V;
            Vsum  += V;
            nV++;
        }
        if (nframes >= n_alloc)
        {
            n_alloc += 100;
            for (i = 0; i < gnx; i++)
            {
                srenew(c1[i], n_alloc);
            }
        }
        for (i = 0; i < gnx; i += DIM)
        {
            c1[i+XX][nframes] = fr.v[i/DIM][XX];
            c1[i+YY][nframes] = fr.v[i/DIM][YY];
            c1[i+ZZ][nframes] = fr.v[i/DIM][ZZ];
        }

        t1 = fr.time;

        nframes++;
    }
    while (read_next_frame(oenv, status, &fr));

    close_trj(status);

    dt = (t1-t0)/(nframes-1);
    if (nV > 0)
    {
        V = Vsum/nV;
    }
    if (bVerbose)
    {
        printf("Going to do %d fourier transforms of length %d. Hang on.\n",
               gnx, nframes);
    }
    low_do_autocorr(NULL, oenv, NULL, nframes, gnx, nframes, c1, dt, eacNormal, 0, FALSE,
                    FALSE, FALSE, -1, -1, 0, 0);
    snew(dos, DOS_NR);
    for (j = 0; (j < DOS_NR); j++)
    {
        snew(dos[j], nframes+4);
    }

    if (bVerbose)
    {
        printf("Going to merge the ACFs into the mass-weighted and plain ACF\n");
    }
    for (i = 0; (i < gnx); i += DIM)
    {
        mi = top.atoms.atom[i/DIM].m;
        for (j = 0; (j < nframes/2); j++)
        {
            c1j            = (c1[i+XX][j] + c1[i+YY][j] + c1[i+ZZ][j]);
            dos[VACF][j]  += c1j/Natom;
            dos[MVACF][j] += mi*c1j;
        }
    }
    fp = xvgropen(opt2fn("-vacf", NFILE, fnm), "Velocity ACF",
                  "Time (ps)", "C(t)", oenv);
    snew(tt, nframes/2);
    for (j = 0; (j < nframes/2); j++)
    {
        tt[j] = j*dt;
        fprintf(fp, "%10g  %10g\n", tt[j], dos[VACF][j]);
    }
    xvgrclose(fp);
    fp = xvgropen(opt2fn("-mvacf", NFILE, fnm), "Mass-weighted velocity ACF",
                  "Time (ps)", "C(t)", oenv);
    for (j = 0; (j < nframes/2); j++)
    {
        fprintf(fp, "%10g  %10g\n", tt[j], dos[MVACF][j]);
    }
    xvgrclose(fp);

    if ((fftcode = gmx_fft_init_1d_real(&fft, nframes/2,
                                        GMX_FFT_FLAG_NONE)) != 0)
    {
        gmx_fatal(FARGS, "gmx_fft_init_1d_real returned %d", fftcode);
    }
    if ((fftcode = gmx_fft_1d_real(fft, GMX_FFT_REAL_TO_COMPLEX,
                                   (void *)dos[MVACF], (void *)dos[DOS])) != 0)
    {
        gmx_fatal(FARGS, "gmx_fft_1d_real returned %d", fftcode);
    }

    /* First compute the DoS */
    /* Magic factor of 8 included now. */
    bfac = 8*dt*beta/2;
    dos2 = 0;
    snew(nu, nframes/4);
    for (j = 0; (j < nframes/4); j++)
    {
        nu[j] = 2*j/(t1-t0);
        dos2 += sqr(dos[DOS][2*j]) + sqr(dos[DOS][2*j+1]);
        if (bAbsolute)
        {
            dos[DOS][j] = bfac*sqrt(sqr(dos[DOS][2*j]) + sqr(dos[DOS][2*j+1]));
        }
        else
        {
            dos[DOS][j] = bfac*dos[DOS][2*j];
        }
    }
    /* Normalize it */
    dostot = evaluate_integral(nframes/4, nu, dos[DOS], NULL, nframes/4, &stddev);
    if (bNormalize)
    {
        for (j = 0; (j < nframes/4); j++)
        {
            dos[DOS][j] *= 3*Natom/dostot;
        }
    }

    /* Now analyze it */
    DoS0 = dos[DOS][0];

    /* Note this eqn. is incorrect in Pascal2011a! */
    Delta = ((2*DoS0/(9*Natom))*sqrt(M_PI*BOLTZ*Temp*Natom/tmass)*
             pow((Natom/V), 1.0/3.0)*pow(6/M_PI, 2.0/3.0));
    f     = calc_fluidicity(Delta, toler);
    y     = calc_y(f, Delta, toler);
    z     = calc_compress(y);
    Sig   = BOLTZ*(5.0/2.0+log(2*M_PI*BOLTZ*Temp/(sqr(PLANCK))*V/(f*Natom)));
    Shs   = Sig+calc_Shs(f, y);
    rho   = (tmass*AMU)/(V*NANO*NANO*NANO);
    sigHS = pow(6*y*V/(M_PI*Natom), 1.0/3.0);

    fprintf(fplog, "System = \"%s\"\n", title);
    fprintf(fplog, "Nmol = %d\n", Nmol);
    fprintf(fplog, "Natom = %d\n", Natom);
    fprintf(fplog, "dt = %g ps\n", dt);
    fprintf(fplog, "tmass = %g amu\n", tmass);
    fprintf(fplog, "V = %g nm^3\n", V);
    fprintf(fplog, "rho = %g g/l\n", rho);
    fprintf(fplog, "T = %g K\n", Temp);
    fprintf(fplog, "beta = %g mol/kJ\n", beta);

    fprintf(fplog, "\nDoS parameters\n");
    fprintf(fplog, "Delta = %g\n", Delta);
    fprintf(fplog, "fluidicity = %g\n", f);
    fprintf(fplog, "hard sphere packing fraction = %g\n", y);
    fprintf(fplog, "hard sphere compressibility = %g\n", z);
    fprintf(fplog, "ideal gas entropy = %g\n", Sig);
    fprintf(fplog, "hard sphere entropy = %g\n", Shs);
    fprintf(fplog, "sigma_HS = %g nm\n", sigHS);
    fprintf(fplog, "DoS0 = %g\n", DoS0);
    fprintf(fplog, "Dos2 = %g\n", dos2);
    fprintf(fplog, "DoSTot = %g\n", dostot);

    /* Now compute solid (2) and diffusive (3) components */
    fp = xvgropen(opt2fn("-dos", NFILE, fnm), "Density of states",
                  bRecip ? "E (cm\\S-1\\N)" : "\\f{12}n\\f{4} (1/ps)",
                  "\\f{4}S(\\f{12}n\\f{4})", oenv);
    xvgr_legend(fp, asize(DoSlegend), DoSlegend, oenv);
    recip_fac = bRecip ? (1e7/SPEED_OF_LIGHT) : 1.0;
    for (j = 0; (j < nframes/4); j++)
    {
        dos[DOS_DIFF][j]  = DoS0/(1+sqr(DoS0*M_PI*nu[j]/(6*f*Natom)));
        dos[DOS_SOLID][j] = dos[DOS][j]-dos[DOS_DIFF][j];
        fprintf(fp, "%10g  %10g  %10g  %10g\n",
                recip_fac*nu[j],
                dos[DOS][j]/recip_fac,
                dos[DOS_SOLID][j]/recip_fac,
                dos[DOS_DIFF][j]/recip_fac);
    }
    xvgrclose(fp);

    /* Finally analyze the results! */
    wCdiff = 0.5;
    wSdiff = Shs/(3*BOLTZ); /* Is this correct? */
    wEdiff = 0.5;
    wAdiff = wEdiff-wSdiff;
    for (j = 0; (j < nframes/4); j++)
    {
        dos[DOS_CP][j] = (dos[DOS_DIFF][j]*wCdiff +
                          dos[DOS_SOLID][j]*wCsolid(nu[j], beta));
        dos[DOS_S][j]  = (dos[DOS_DIFF][j]*wSdiff +
                          dos[DOS_SOLID][j]*wSsolid(nu[j], beta));
        dos[DOS_A][j]  = (dos[DOS_DIFF][j]*wAdiff +
                          dos[DOS_SOLID][j]*wAsolid(nu[j], beta));
        dos[DOS_E][j]  = (dos[DOS_DIFF][j]*wEdiff +
                          dos[DOS_SOLID][j]*wEsolid(nu[j], beta));
    }
    DiffCoeff = evaluate_integral(nframes/2, tt, dos[VACF], NULL, nframes/2, &stddev);
    DiffCoeff = 1000*DiffCoeff/3.0;
    fprintf(fplog, "Diffusion coefficient from VACF %g 10^-5 cm^2/s\n",
            DiffCoeff);
    fprintf(fplog, "Diffusion coefficient from DoS %g 10^-5 cm^2/s\n",
            1000*DoS0/(12*tmass*beta));

    cP = BOLTZ * evaluate_integral(nframes/4, nu, dos[DOS_CP], NULL,
                                   nframes/4, &stddev);
    fprintf(fplog, "Heat capacity %g J/mol K\n", 1000*cP/Nmol);

    /*
       S  = BOLTZ * evaluate_integral(nframes/4,nu,dos[DOS_S],NULL,
                                   nframes/4,&stddev);
       fprintf(fplog,"Entropy %g J/mol K\n",1000*S/Nmol);
       A  = BOLTZ * evaluate_integral(nframes/4,nu,dos[DOS_A],NULL,
                                   nframes/4,&stddev);
       fprintf(fplog,"Helmholtz energy %g kJ/mol\n",A/Nmol);
       E  = BOLTZ * evaluate_integral(nframes/4,nu,dos[DOS_E],NULL,
                                   nframes/4,&stddev);
       fprintf(fplog,"Internal energy %g kJ/mol\n",E/Nmol);
     */
    fprintf(fplog, "\nArrivederci!\n");
    gmx_fio_fclose(fplog);

    do_view(oenv, ftp2fn(efXVG, NFILE, fnm), "-nxy");

    thanx(stderr);

    return 0;
}
Esempio n. 3
0
int gmx_dos(int argc, char *argv[])
{
    const char         *desc[] = {
        "[THISMODULE] computes the Density of States from a simulations.",
        "In order for this to be meaningful the velocities must be saved",
        "in the trajecotry with sufficiently high frequency such as to cover",
        "all vibrations. For flexible systems that would be around a few fs",
        "between saving. Properties based on the DoS are printed on the",
        "standard output."
        "Note that the density of states is calculated from the mass-weighted",
        "autocorrelation, and by default only from the square of the real",
        "component rather than absolute value. This means the shape can differ",
        "substantially from the plain vibrational power spectrum you can",
        "calculate with gmx velacc."
    };
    const char         *bugs[] = {
        "This program needs a lot of memory: total usage equals the number of atoms times 3 times number of frames times 4 (or 8 when run in double precision)."
    };
    FILE               *fp, *fplog;
    t_topology          top;
    int                 ePBC = -1;
    t_trxframe          fr;
    matrix              box;
    int                 gnx;
    real                t0, t1;
    t_trxstatus        *status;
    int                 nV, nframes, n_alloc, i, j, fftcode, Nmol, Natom;
    double              rho, dt, Vsum, V, tmass, dostot, dos2;
    real              **c1, **dos, mi, beta, bfac, *nu, *tt, stddev, c1j;
    gmx_output_env_t   *oenv;
    gmx_fft_t           fft;
    double              cP, DiffCoeff, Delta, f, y, z, sigHS, Shs, Sig, DoS0, recip_fac;
    double              wCdiff, wSdiff, wAdiff, wEdiff;
    int                 grpNatoms;
    int                *index;
    char               *grpname;
    double              invNormalize;
    gmx_bool            normalizeAutocorrelation;

    static     gmx_bool bVerbose = TRUE, bAbsolute = FALSE, bNormalizeDos = FALSE;
    static     gmx_bool bRecip   = FALSE;
    static     real     Temp     = 298.15, toler = 1e-6;

    t_pargs             pa[]     = {
        {   "-v", FALSE, etBOOL, {&bVerbose},
            "Be loud and noisy."
        },
        {   "-recip", FALSE, etBOOL, {&bRecip},
            "Use cm^-1 on X-axis instead of 1/ps for DoS plots."
        },
        {   "-abs", FALSE, etBOOL, {&bAbsolute},
            "Use the absolute value of the Fourier transform of the VACF as the Density of States. Default is to use the real component only"
        },
        {   "-normdos", FALSE, etBOOL, {&bNormalizeDos},
            "Normalize the DoS such that it adds up to 3N. This should usually not be necessary."
        },
        {   "-T", FALSE, etREAL, {&Temp},
            "Temperature in the simulation"
        },
        {   "-toler", FALSE, etREAL, {&toler},
            "[HIDDEN]Tolerance when computing the fluidicity using bisection algorithm"
        }
    };

    t_filenm            fnm[] = {
        { efTRN, "-f",    NULL,    ffREAD  },
        { efTPR, "-s",    NULL,    ffREAD  },
        { efNDX, NULL,    NULL,    ffOPTRD },
        { efXVG, "-vacf", "vacf",  ffWRITE },
        { efXVG, "-mvacf", "mvacf", ffWRITE },
        { efXVG, "-dos",  "dos",   ffWRITE },
        { efLOG, "-g",    "dos",   ffWRITE },
    };
#define NFILE asize(fnm)
    int                 npargs;
    t_pargs            *ppa;
    const char         *DoSlegend[] = {
        "DoS(v)", "DoS(v)[Solid]", "DoS(v)[Diff]"
    };

    npargs = asize(pa);
    ppa    = add_acf_pargs(&npargs, pa);
    if (!parse_common_args(&argc, argv, PCA_CAN_VIEW | PCA_CAN_TIME,
                           NFILE, fnm, npargs, ppa, asize(desc), desc,
                           asize(bugs), bugs, &oenv))
    {
        return 0;
    }

    beta = 1/(Temp*BOLTZ);

    fplog = gmx_fio_fopen(ftp2fn(efLOG, NFILE, fnm), "w");
    fprintf(fplog, "Doing density of states analysis based on trajectory.\n");
    please_cite(fplog, "Pascal2011a");
    please_cite(fplog, "Caleman2011b");

    read_tps_conf(ftp2fn(efTPR, NFILE, fnm), &top, &ePBC, NULL, NULL, box, TRUE);

    /* Handle index groups */
    get_index(&top.atoms, ftp2fn_null(efNDX, NFILE, fnm), 1, &grpNatoms, &index, &grpname);

    V     = det(box);
    tmass = 0;
    for (i = 0; i < grpNatoms; i++)
    {
        tmass += top.atoms.atom[index[i]].m;
    }

    Natom = grpNatoms;
    Nmol  = calcMoleculesInIndexGroup(&top.mols, top.atoms.nr, index, grpNatoms);
    gnx   = Natom*DIM;

    /* Correlation stuff */
    snew(c1, gnx);
    for (i = 0; (i < gnx); i++)
    {
        c1[i] = NULL;
    }

    read_first_frame(oenv, &status, ftp2fn(efTRN, NFILE, fnm), &fr, TRX_NEED_V);
    t0 = fr.time;

    n_alloc = 0;
    nframes = 0;
    Vsum    = 0;
    nV      = 0;
    do
    {
        if (fr.bBox)
        {
            V      = det(fr.box);
            Vsum  += V;
            nV++;
        }
        if (nframes >= n_alloc)
        {
            n_alloc += 100;
            for (i = 0; i < gnx; i++)
            {
                srenew(c1[i], n_alloc);
            }
        }
        for (i = 0; i < gnx; i += DIM)
        {
            c1[i+XX][nframes] = fr.v[index[i/DIM]][XX];
            c1[i+YY][nframes] = fr.v[index[i/DIM]][YY];
            c1[i+ZZ][nframes] = fr.v[index[i/DIM]][ZZ];
        }

        t1 = fr.time;

        nframes++;
    }
    while (read_next_frame(oenv, status, &fr));

    close_trj(status);

    dt = (t1-t0)/(nframes-1);
    if (nV > 0)
    {
        V = Vsum/nV;
    }
    if (bVerbose)
    {
        printf("Going to do %d fourier transforms of length %d. Hang on.\n",
               gnx, nframes);
    }
    /* Unfortunately the -normalize program option for the autocorrelation
     * function calculation is added as a hack with a static variable in the
     * autocorrelation.c source. That would work if we called the normal
     * do_autocorr(), but this routine overrides that by directly calling
     * the low-level functionality. That unfortunately leads to ignoring the
     * default value for the option (which is to normalize).
     * Since the absolute value seems to be important for the subsequent
     * analysis below, we detect the value directly from the option, calculate
     * the autocorrelation without normalization, and then apply the
     * normalization just to the autocorrelation output
     * (or not, if the user asked for a non-normalized autocorrelation).
     */
    normalizeAutocorrelation = opt2parg_bool("-normalize", npargs, ppa);

    /* Note that we always disable normalization here, regardless of user settings */
    low_do_autocorr(NULL, oenv, NULL, nframes, gnx, nframes, c1, dt, eacNormal, 0, FALSE,
                    FALSE, FALSE, -1, -1, 0);
    snew(dos, DOS_NR);
    for (j = 0; (j < DOS_NR); j++)
    {
        snew(dos[j], nframes+4);
    }

    if (bVerbose)
    {
        printf("Going to merge the ACFs into the mass-weighted and plain ACF\n");
    }
    for (i = 0; (i < gnx); i += DIM)
    {
        mi = top.atoms.atom[index[i/DIM]].m;
        for (j = 0; (j < nframes/2); j++)
        {
            c1j            = (c1[i+XX][j] + c1[i+YY][j] + c1[i+ZZ][j]);
            dos[VACF][j]  += c1j/Natom;
            dos[MVACF][j] += mi*c1j;
        }
    }

    fp = xvgropen(opt2fn("-vacf", NFILE, fnm), "Velocity autocorrelation function",
                  "Time (ps)", "C(t)", oenv);
    snew(tt, nframes/2);

    invNormalize = normalizeAutocorrelation ? 1.0/dos[VACF][0] : 1.0;

    for (j = 0; (j < nframes/2); j++)
    {
        tt[j] = j*dt;
        fprintf(fp, "%10g  %10g\n", tt[j], dos[VACF][j] * invNormalize);
    }
    xvgrclose(fp);

    fp = xvgropen(opt2fn("-mvacf", NFILE, fnm), "Mass-weighted velocity autocorrelation function",
                  "Time (ps)", "C(t)", oenv);

    invNormalize = normalizeAutocorrelation ? 1.0/dos[VACF][0] : 1.0;

    for (j = 0; (j < nframes/2); j++)
    {
        fprintf(fp, "%10g  %10g\n", tt[j], dos[MVACF][j] * invNormalize);
    }
    xvgrclose(fp);

    if ((fftcode = gmx_fft_init_1d_real(&fft, nframes/2,
                                        GMX_FFT_FLAG_NONE)) != 0)
    {
        gmx_fatal(FARGS, "gmx_fft_init_1d_real returned %d", fftcode);
    }
    if ((fftcode = gmx_fft_1d_real(fft, GMX_FFT_REAL_TO_COMPLEX,
                                   (void *)dos[MVACF], (void *)dos[DOS])) != 0)
    {
        gmx_fatal(FARGS, "gmx_fft_1d_real returned %d", fftcode);
    }

    /* First compute the DoS */
    /* Magic factor of 8 included now. */
    bfac = 8*dt*beta/2;
    dos2 = 0;
    snew(nu, nframes/4);
    for (j = 0; (j < nframes/4); j++)
    {
        nu[j] = 2*j/(t1-t0);
        dos2 += gmx::square(dos[DOS][2*j]) + gmx::square(dos[DOS][2*j+1]);
        if (bAbsolute)
        {
            dos[DOS][j] = bfac*std::hypot(dos[DOS][2*j], dos[DOS][2*j+1]);
        }
        else
        {
            dos[DOS][j] = bfac*dos[DOS][2*j];
        }
    }
    /* Normalize it */
    dostot = evaluate_integral(nframes/4, nu, dos[DOS], NULL, nframes/4, &stddev);
    if (bNormalizeDos)
    {
        for (j = 0; (j < nframes/4); j++)
        {
            dos[DOS][j] *= 3*Natom/dostot;
        }
    }

    /* Now analyze it */
    DoS0 = dos[DOS][0];

    /* Note this eqn. is incorrect in Pascal2011a! */
    Delta = ((2*DoS0/(9*Natom))*std::sqrt(M_PI*BOLTZ*Temp*Natom/tmass)*
             std::pow((Natom/V), 1.0/3.0)*std::pow(6.0/M_PI, 2.0/3.0));
    f     = calc_fluidicity(Delta, toler);
    y     = calc_y(f, Delta, toler);
    z     = calc_compress(y);
    Sig   = BOLTZ*(5.0/2.0+std::log(2*M_PI*BOLTZ*Temp/(gmx::square(PLANCK))*V/(f*Natom)));
    Shs   = Sig+calc_Shs(f, y);
    rho   = (tmass*AMU)/(V*NANO*NANO*NANO);
    sigHS = std::cbrt(6*y*V/(M_PI*Natom));

    fprintf(fplog, "System = \"%s\"\n", *top.name);
    fprintf(fplog, "Nmol = %d\n", Nmol);
    fprintf(fplog, "Natom = %d\n", Natom);
    fprintf(fplog, "dt = %g ps\n", dt);
    fprintf(fplog, "tmass = %g amu\n", tmass);
    fprintf(fplog, "V = %g nm^3\n", V);
    fprintf(fplog, "rho = %g g/l\n", rho);
    fprintf(fplog, "T = %g K\n", Temp);
    fprintf(fplog, "beta = %g mol/kJ\n", beta);

    fprintf(fplog, "\nDoS parameters\n");
    fprintf(fplog, "Delta = %g\n", Delta);
    fprintf(fplog, "fluidicity = %g\n", f);
    fprintf(fplog, "hard sphere packing fraction = %g\n", y);
    fprintf(fplog, "hard sphere compressibility = %g\n", z);
    fprintf(fplog, "ideal gas entropy = %g\n", Sig);
    fprintf(fplog, "hard sphere entropy = %g\n", Shs);
    fprintf(fplog, "sigma_HS = %g nm\n", sigHS);
    fprintf(fplog, "DoS0 = %g\n", DoS0);
    fprintf(fplog, "Dos2 = %g\n", dos2);
    fprintf(fplog, "DoSTot = %g\n", dostot);

    /* Now compute solid (2) and diffusive (3) components */
    fp = xvgropen(opt2fn("-dos", NFILE, fnm), "Density of states",
                  bRecip ? "E (cm\\S-1\\N)" : "\\f{12}n\\f{4} (1/ps)",
                  "\\f{4}S(\\f{12}n\\f{4})", oenv);
    xvgr_legend(fp, asize(DoSlegend), DoSlegend, oenv);
    recip_fac = bRecip ? (1e7/SPEED_OF_LIGHT) : 1.0;
    for (j = 0; (j < nframes/4); j++)
    {
        dos[DOS_DIFF][j]  = DoS0/(1+gmx::square(DoS0*M_PI*nu[j]/(6*f*Natom)));
        dos[DOS_SOLID][j] = dos[DOS][j]-dos[DOS_DIFF][j];
        fprintf(fp, "%10g  %10g  %10g  %10g\n",
                recip_fac*nu[j],
                dos[DOS][j]/recip_fac,
                dos[DOS_SOLID][j]/recip_fac,
                dos[DOS_DIFF][j]/recip_fac);
    }
    xvgrclose(fp);

    /* Finally analyze the results! */
    wCdiff = 0.5;
    wSdiff = Shs/(3*BOLTZ); /* Is this correct? */
    wEdiff = 0.5;
    wAdiff = wEdiff-wSdiff;
    for (j = 0; (j < nframes/4); j++)
    {
        dos[DOS_CP][j] = (dos[DOS_DIFF][j]*wCdiff +
                          dos[DOS_SOLID][j]*wCsolid(nu[j], beta));
        dos[DOS_S][j]  = (dos[DOS_DIFF][j]*wSdiff +
                          dos[DOS_SOLID][j]*wSsolid(nu[j], beta));
        dos[DOS_A][j]  = (dos[DOS_DIFF][j]*wAdiff +
                          dos[DOS_SOLID][j]*wAsolid(nu[j], beta));
        dos[DOS_E][j]  = (dos[DOS_DIFF][j]*wEdiff +
                          dos[DOS_SOLID][j]*wEsolid(nu[j], beta));
    }
    DiffCoeff = evaluate_integral(nframes/2, tt, dos[VACF], NULL, nframes/2, &stddev);
    DiffCoeff = 1000*DiffCoeff/3.0;
    fprintf(fplog, "Diffusion coefficient from VACF %g 10^-5 cm^2/s\n",
            DiffCoeff);
    fprintf(fplog, "Diffusion coefficient from DoS %g 10^-5 cm^2/s\n",
            1000*DoS0/(12*tmass*beta));

    cP = BOLTZ * evaluate_integral(nframes/4, nu, dos[DOS_CP], NULL,
                                   nframes/4, &stddev);
    fprintf(fplog, "Heat capacity %g J/mol K\n", 1000*cP/Nmol);
    fprintf(fplog, "\nArrivederci!\n");
    gmx_fio_fclose(fplog);

    do_view(oenv, ftp2fn(efXVG, NFILE, fnm), "-nxy");

    return 0;
}