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xiaoqiu007新蟲 (小有名氣)
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[求助]
5.0.2版PWSCF電聲耦合常數(shù)的計(jì)算過(guò)程解讀
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跟上木蟲上發(fā)的這個(gè)熱帖:http://www.gaoyang168.com/bbs/viewthread.php?tid=6086352&fpage=1,也請(qǐng)教幾個(gè)關(guān)于5.0.2版PWSCF電聲耦合常數(shù)的計(jì)算問(wèn)題,希望能得到廣大同仁的指點(diǎn),我也會(huì)即時(shí)匯報(bào)我的計(jì)算進(jìn)展。 5.0.2版計(jì)算電聲耦合常數(shù)分為以下幾個(gè)步驟: 1. make a self-consistent calculation for Al using a dense grid of k-points. The dense grid must contain all k and k+q grid points used in the subsequent electron-phonon calculation and must be dense enough to produce accurate el-phon coefficients (in particular the double-delta integral at Ef is very critical). 問(wèn)題1:第一步就涉及q點(diǎn)和k點(diǎn)設(shè)置問(wèn)題,例子中是設(shè)置成4 :2 :1的關(guān)系,即:16x16x16, 8x8x8, 4x4x4。請(qǐng)問(wèn)q點(diǎn)的設(shè)置依據(jù)是什么?一般應(yīng)設(shè)置成多少合適? 什么是 the double-delta integral at Ef ? 2. make aself-consistent calculation for Al using a grid of k-points that is suitable for good self-consistency and phonon calculation.This example uses a (888) MP grid. 3. make the phonon and electron-phonon calculation for the grid of q-points. Specify elph=.true., and the name of a file where the derivative of the potential is stored "fildvscf".This example uses a (444) MP grid of q-points (nq1=4, nq2=4, nq3=4). The output contains the results for the el-ph coefficient at each q-point lambda(q), gamma(q), and the double-delta integral at several values of the gaussian broadening (set in filePH/elphon.f90). These are useful for convergence testing. (input=al.elph.in,output=al.elph.out) The results are also written into outputfiles "a2Fq2r.*", one per value of the gaussian broadening, for further use. 問(wèn)題2:第三步中(1)5.0.2新版在ph.x步驟設(shè)置 electron_phonon='interpolated', 以前的老版本是設(shè)成:elph=.true.,請(qǐng)問(wèn)另個(gè)參數(shù)的區(qū)別在哪里? (2)convergence testing是算完之后測(cè)試? gaussian broadening 對(duì)計(jì)算結(jié)果有什么影響? 4. Bring to r-space both force constants and el-phon coefficients using "q2r.x" Output in files "a2Fmatdyn.*", one per value of the gaussian broadening 問(wèn)題3:第四步q2r.x,為什么要轉(zhuǎn)換到實(shí)空間? 與gaussian broadening 有什么關(guān)系?這一步是必須的嗎? 5. Calculate gamma on selected lines using "matdyn.x" (dos=.false.) 問(wèn)題4: 這一步是在計(jì)算聲子色散曲線,它是計(jì)算電聲耦合常數(shù)必須的步驟嗎? 6. Calculate lambda coefficient (in file"lambda" and the a^2F(omega)function using "matdyn.x" (dos=.true.) 問(wèn)題5: 這一步感覺是在計(jì)算聲子態(tài)密度,請(qǐng)問(wèn)該步能同時(shí)給出 lambda coefficient和a^2F(omega) function 嗎? 7. Calculate lambda coefficient (in "lambda.out" and Tc using "lambda.x"問(wèn)題6: 計(jì)算仍在進(jìn)行中,請(qǐng)問(wèn)有過(guò)計(jì)算經(jīng)歷的同仁,新版通過(guò)這一步可以直接算出Tc嗎? 綜上,感覺第5步,第6步似乎不是計(jì)算電聲耦合常數(shù)必須的步驟,不知理解是否正確。 完整的例子文件如下所示: # #########SCF at dense k-mesh, good enough forelectronic DOS 【多密算密】 ####### # cat >al.scf.fit.in << EOF &control calculation='scf' restart_mode='from_scratch', prefix='al', pseudo_dir = '$PSEUDO_DIR/', outdir='$TMP_DIR/' / &system ibrav= 2, celldm(1) =7.5, nat= 1, ntyp= 1, ecutwfc =15.0, occupations='smearing',smearing='methfessel-paxton', degauss=0.05, la2F= .true., / &electrons conv_thr = 1.0d-8 mixing_beta = 0.7 / ATOMIC_SPECIES Al 26.98 Al.pz-vbc.UPF ATOMIC_POSITIONS Al 0.00 0.00 0.00 K_POINTS{automatic} 16 16 16 0 0 0 EOF $ECHO " running the scf calculation with densek-point grid...\c" $PW_COMMAND < al.scf.fit.in > al.scf.fit.out # ########## SCFat k-mesh good enough for phonons【多好算好!】###### # cat > al.scf.in<< EOF &control calculation='scf' restart_mode='from_scratch', prefix='al', pseudo_dir = '$PSEUDO_DIR/', outdir='$TMP_DIR/' / &system ibrav= 2, celldm(1) =7.5, nat= 1, ntyp= 1, ecutwfc =15.0, occupations='smearing',smearing='methfessel-paxton', degauss=0.05 / &electrons conv_thr = 1.0d-8 mixing_beta = 0.7 / ATOMIC_SPECIES Al 26.98 Al.pz-vbc.UPF #### Pseudopotential type: NORMCONS ATOMIC_POSITIONS Al 0.00 0.00 0.00 K_POINTS{automatic} 8 8 8 00 0 EOF $ECHO " running the scf calculation...\c" $PW_COMMAND <al.scf.in > al.scf.out ############################# cat >al.elph.in << EOF Electron-phonon coefficients for Al &inputph tr2_ph=1.0d-10, prefix='al', fildvscf='aldv', amass(1)=26.98, outdir='$TMP_DIR/', fildyn='al.dyn', electron_phonon='interpolated', #與elph=.true.,的區(qū)別何在? trans=.true., ldisp=.true. nq1=4, nq2=4, nq3=4 / EOF $ECHO " running the el-ph calculation...\c" $PH_COMMAND <al.elph.in > al.elph.out # # q2r and matdyn # cat > q2r.in<< EOF &input zasr='simple', fildyn='al.dyn', flfrc='Al444.fc', la2F=.true. / EOF $ECHO " running q2r...\c" $Q2R_COMMAND < q2r.in > q2r.out # ###########聲子譜:聲子色散曲線#### cat >matdyn.in.freq << EOF &input asr='simple', amass(1)=26.98, flfrc='Al444.fc', flfrq='Al444.freq', la2F=.true., dos=.false. / 19 0.000 0.0 0.0 0.0 0.125 0.0 0.0 0.0 0.250 0.0 0.0 0.0 0.375 0.0 0.0 0.0 0.500 0.0 0.0 0.0 0.750 0.0 0.0 0.0 1.000 0.0 0.0 0.0 0.825 0.125 0.125 0.0 0.750 0.250 0.250 0.0 0.625 0.375 0.375 0.0 0.500 0.500 0.500 0.0 0.325 0.325 0.325 0.0 0.250 0.250 0.250 0.0 0.125 0.125 0.125 0.0 0.000 0.000 0.000 0.0 0.125 0.125 0.000 0.0 0.250 0.250 0.000 0.0 0.325 0.325 0.000 0.0 0.500 0.500 0.000 0.0 EOF $ECHO " running matdyn for frequencycalculation...\c" $MATDYN_COMMAND< matdyn.in.freq > matdyn.out.freq check_failure $? ###########聲子態(tài)密度計(jì)算#### cat >matdyn.in.dos << EOF &input asr='simple', amass(1)=26.98, flfrc='Al444.fc', flfrq='Al444.freq', la2F=.true., dos=.true. fldos='phonon.dos', nk1=10, nk2=10, nk3=10,ndos=50 / EOF $ECHO " running matdyn for a2F(omega) calculation...\c" $MATDYN_COMMAND< matdyn.in.dos > matdyn.out.dos check_failure $? $ECHO " done" # # ############Eliashberg函數(shù)alpha^2 F和電聲耦合常數(shù)lamda計(jì)算######## cat > lambda.in<< EOF 10 0.12 1 ! emax (something more thanhighest phonon mode in THz), degauss, smearing method 8 ! Number of q-points for which EPC is calculated, 0.0000000 0.0000000 0.0000000 1.00 ! the first q-point, use kpoints.x program to calculate -0.2500000 -0.2500000 0.2500000 8.00 ! q-points and their weight -0.5000000 -0.5000000 0.5000000 4.00 ! 0.0000000 0.0000000 0.5000000 6.00 ! 4th q-point, qx,qy,qz -0.2500000 -0.2500000 0.7500000 24.00 ! -0.5000000 -0.5000000 1.0000000 12.00 ! 0.0000000 0.0000000 1.0000000 3.00 ! -0.5000000 0.0000000 1.0000000 6.00 ! the last q-point elph. 0.000000.0.000000. 0.000000 ! elph output file names, elph.-0.250000.0.250000.-0.250000 ! in the same order as the q-points before elph.0.500000.-0.500000. 0.500000 elph. 0.000000.0.500000. 0.000000 elph.0.750000.-0.250000. 0.750000 elph. 0.500000.0.000000. 0.500000 elph.0.000000.-1.000000. 0.000000 elph.-0.500000.-1.000000.0.000000 0.10 ! \mu the Coloumbcoefficient in the modified ! Allen-Dynes formulafor T_c (via \omega_log) EOF $ECHO " running lambda.x for lambdacalculation...\c" $LAMBDA_COMMAND< lambda.in > lambda.out |
新蟲 (小有名氣)
銅蟲 (初入文壇)
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