gruneisen1D.py 文件源码

def compute_grun_along_one_direction(nq,modes,ngeo,cgeo,celldmsx,freqgeo,rangegeo,xindex=0):
    """
    Compute the Gruneisen parameters along one direction.
    This function uses a 1-dimensional polynomial of fourth degree to fit the 
    frequencies along a certain direction (along a and c axis in hexagonal systems
    for example). 
    """
    # set a numpy array of volumes for the fit (n=5)
    xtemp=[]
    for igeo in rangegeo:
        xtemp.append(celldmsx[igeo,xindex])
    x=np.array(xtemp)

    grun=[]
    for iq in range(0,nq):
        grunq=[]
        for ifreq in range(0,modes):
            ytemp=[]
            for igeo in rangegeo:
                ytemp.append(freqgeo[igeo,iq,ifreq])
            y=np.array(ytemp)    
            z=np.polyfit(x, y, 4)
            p=np.poly1d(z)
            pderiv=np.polyder(p)
            if freqgeo[cgeo[xindex],iq,ifreq]<1E-3:
                grunq.append(0.0)
            else:
                grunq.append(pderiv(celldmsx[cgeo[xindex],xindex])/freqgeo[cgeo[xindex],iq,ifreq]) #*celldmsx[cgeo[xindex],xindex])
        grun.append(grunq)

    return np.array(grun)    


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