Basis.py 文件源码

def table_es(nstate,nparticle,spinz,dtype=np.int64):
    '''
    This function generates the table of binary representations of a particle-conserved and spin-conserved basis.
    '''
    n,nup,ndw=nstate/2,(nparticle+int(2*spinz))/2,(nparticle-int(2*spinz))/2
    result=np.zeros(factorial(n)/factorial(nup)/factorial(n-nup)*factorial(n)/factorial(ndw)/factorial(n-ndw),dtype=dtype)
    buff_up=list(combinations(xrange(1,2*n,2),nup))
    buff_dw=list(combinations(xrange(0,2*n,2),ndw))
    count=0
    for vup in buff_up:
        buff=0
        for num in vup:
            buff+=(1<<num)
        for vdw in buff_dw:
            basis=buff
            for num in vdw:
                basis+=(1<<num)
            result[count]=basis
            count+=1
    result.sort()
    return result