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zhangfan2192金蟲(chóng) (著名寫(xiě)手)
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[交流]
【其他】vasp neb 計(jì)算討論 已有11人參與
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希望各位用vasp的蟲(chóng)友能夠討論下neb計(jì)算中的注意事項(xiàng): 不知道為什么,我在用neb計(jì)算過(guò)度態(tài)的時(shí)候總是感覺(jué)計(jì)算結(jié)果不是很理想,很難找到自己需要的結(jié)果,比如說(shuō)計(jì)算的8個(gè)image的能量是單調(diào)上升或下降的,而不是拋物線形狀,不知道大家在計(jì)算的時(shí)候遇到這樣的情況沒(méi),如果遇到的話大家都是怎么解決的?相信現(xiàn)在用vasp軟件的不在少數(shù),歡迎大家積極討論建議! |
VASP | first principle | 第一性原理和電化學(xué) | vasp計(jì)算總結(jié) |
計(jì)算資料收集byFrank |

榮譽(yù)版主 (職業(yè)作家)
做NEB要保證初態(tài)和末態(tài)處于能量極小值點(diǎn)(局域的或是全局的),也就是初態(tài)和末態(tài)都是經(jīng)過(guò)優(yōu)化之后的,在這個(gè)基礎(chǔ)上再做中間的imagines可能就可以避免單調(diào)上升和下降了。個(gè)人觀點(diǎn),歡迎指正。![]() [ Last edited by uuv2010 on 2010-7-6 at 10:23 ] |
木蟲(chóng) (著名寫(xiě)手)
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為什么LCLIMB=.False.呢?Climbing-Image NEB 能夠幫助找到路徑中的能量最高點(diǎn)。 還有,如果路徑較長(zhǎng),可能還需要增加images 數(shù)量來(lái)保證路徑收斂正確。 再則,如果樓主大概知道反應(yīng)勢(shì)壘,并且很小的話,每一個(gè)image能量的計(jì)算就需要特別精細(xì)了,因?yàn)橐稽c(diǎn)誤差都會(huì)導(dǎo)致結(jié)果和預(yù)期很不一樣。 |

鐵蟲(chóng) (小有名氣)
金蟲(chóng) (著名寫(xiě)手)
金蟲(chóng) (著名寫(xiě)手)

鐵桿木蟲(chóng) (正式寫(xiě)手)
金蟲(chóng) (著名寫(xiě)手)
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INCAR文件如下: SYSTEM = Sul-Fe Startparameter for this Run: NWRITE = 2 verbosity write-flag LPETIM= F write-flag & timer # ISTART = 0 0-new 1-cont 2-samecut job ISPIN = 2 1-no, 2-yes INIWAV = 1 0-jellium WF; 1-random numbers (recomm.) Electronic Relaxation ! ENCUT = 400.00 #Ecut (eV) PREC = Medium * #precission: #Low/Medium/High NELM = 200 max. # of electronic SC steps NELMDL = 5 # of non-consistent steps at the beggining:>0 or <0 EDIFF = 1.0e-4 stopping-criterion for electronic upd. VOSKOWN = 1 ISMEAR = 1 SIGMA = 0.1 ! AMIX = 0.2 ! BMIX = 0.0001 Ionic relaxation EDIFFG = 1.0e-3 stopping-conditions for ionic relax.loop (EDIFF*10) NSW = 200 * # of steps for ionic update (def:0) IBRION = 2 * ionic relax: -1:no move; 0-MD;1-Newton;2-CG;3-damped;4-? ISIF = 2 * calc.stress:0-no;1-tr;2-7 yes; 3-change vol.4-change shape ISYM = 0 symmetry:0-OFF, 1-ON,2-ON+memory conserving for CD POTIM = 0.3 if IBRION=1,2,3:scaling constant forces;IBRION=0,time st. LPLANE = .TRUE. NPAR = 8 IALGO = 48 * algorithm: use only 8 (CG) or 48 (RMM-DIIS) LDIAG = .TRUE. sub-space diagonalisation GGA = 91 * xc-type: PB, PW (86), LM, 91 (Perdew-Wang 91) LWAVE = .F. * write WAVECAR LCHARG = .T. * write CHGCAR and CHG LVTOT = .F. * write the local potential LOCPOT LELF = .F. create ELFCAR file LORBIT = .F. create PROOUT LREAL = Auto ! NEB IMAGES = 8 ! Number of images in the band, excluding endpoints SPRING = -5.0 eV/A2 ! Spring force between images; negative value turns on nudging LCLIMB = .False. ! Flag to turn on the climbing image algorithm |

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