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【求助】有人用有限差分方法計算過G點聲子譜嗎?
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如題,我設置IBRION=5,計算了立方BaTiO3的G點聲子譜,結(jié)果發(fā)現(xiàn)了些問題: INCAR:SYSTEM = BaTiO3 ISTART = 0 ICHARG = 2 ENCUT = 500 LDA = CA NELMIN = 4 NSW = 80 IBRION = 5 POTIM = 0.01 NFREE = 2 PREC = High ALGO = Fast ISIF = 2 ISMEAR = -5 SIGMA = 0.01 LREAL = Auto EDIFF = 1E-5 EDIFFG =-1E-3 AMIX = 0.2 BMIX = 0.0001 AMIX_MAG = 0.8 BMIX_MAG = 0.0001 就是得到的15個特征向量都是沿一個方向的,這個明顯不是簡諧振動模式,比如氧八面體扭曲模式O的移動就不可能是在一個方向上的,而且沒有發(fā)現(xiàn)平移的聲子模式。所以請問這個跟聲子有什么區(qū)別?下面是結(jié)果: Eigenvectors and eigenvalues of the dynamical matrix ---------------------------------------------------- 1 f = 15.439755 THz 97.010840 2PiTHz 515.014765 cm-1 63.853716 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.000000 0.410501 2.003000 0.000000 2.003000 0.000000 0.000000 -0.272451 0.000000 2.003000 2.003000 0.000000 0.000000 -0.790776 2.003000 2.003000 2.003000 0.000000 0.000000 0.363062 0.000000 0.000000 0.000000 0.000000 0.000000 0.010895 2 f = 14.403101 THz 90.497354 2PiTHz 480.435728 cm-1 59.566460 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.128400 0.000000 2.003000 0.000000 2.003000 0.000000 -0.484223 0.000000 0.000000 2.003000 2.003000 0.000000 0.834506 0.000000 2.003000 2.003000 2.003000 0.000000 -0.228456 0.000000 0.000000 0.000000 0.000000 0.000000 0.021191 0.000000 3 f = 9.980407 THz 62.708746 2PiTHz 332.910530 cm-1 41.275660 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 -0.265607 0.000000 0.000000 2.003000 0.000000 2.003000 -0.563172 0.000000 0.000000 0.000000 2.003000 2.003000 0.766038 0.000000 0.000000 2.003000 2.003000 2.003000 0.143725 0.000000 0.000000 0.000000 0.000000 0.000000 -0.069418 0.000000 0.000000 4 f = 9.424248 THz 59.214298 2PiTHz 314.359075 cm-1 38.975572 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.000000 -0.339070 2.003000 0.000000 2.003000 0.000000 0.000000 0.776425 0.000000 2.003000 2.003000 0.000000 0.000000 -0.510194 2.003000 2.003000 2.003000 0.000000 0.000000 -0.144225 0.000000 0.000000 0.000000 0.000000 0.000000 -0.033118 5 f = 6.907624 THz 43.401880 2PiTHz 230.413517 cm-1 28.567645 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.307521 0.000000 2.003000 0.000000 2.003000 0.000000 -0.767570 0.000000 0.000000 2.003000 2.003000 0.000000 -0.532701 0.000000 2.003000 2.003000 2.003000 0.000000 -0.135043 0.000000 0.000000 0.000000 0.000000 0.000000 0.119416 0.000000 6 f = 5.812542 THz 36.521276 2PiTHz 193.885510 cm-1 24.038748 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.000000 0.273711 2.003000 0.000000 2.003000 0.000000 0.000000 0.330617 0.000000 2.003000 2.003000 0.000000 0.000000 0.235149 2.003000 2.003000 2.003000 0.000000 0.000000 0.472789 0.000000 0.000000 0.000000 0.000000 0.000000 -0.732769 7 f = 5.010456 THz 31.481622 2PiTHz 167.130808 cm-1 20.721587 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.370569 0.000000 2.003000 0.000000 2.003000 0.000000 -0.094861 0.000000 0.000000 2.003000 2.003000 0.000000 0.048415 0.000000 2.003000 2.003000 2.003000 0.000000 0.515184 0.000000 0.000000 0.000000 0.000000 0.000000 -0.765455 0.000000 8 f = 4.076207 THz 25.611565 2PiTHz 135.967632 cm-1 16.857844 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.231970 0.000000 0.000000 2.003000 0.000000 2.003000 0.230327 0.000000 0.000000 0.000000 2.003000 2.003000 0.069857 0.000000 0.000000 2.003000 2.003000 2.003000 0.613178 0.000000 0.000000 0.000000 0.000000 0.000000 -0.715732 0.000000 0.000000 9 f = 1.169851 THz 7.350394 2PiTHz 39.022044 cm-1 4.838119 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 -0.179440 0.000000 0.000000 2.003000 0.000000 2.003000 -0.398238 0.000000 0.000000 0.000000 2.003000 2.003000 -0.317558 0.000000 0.000000 2.003000 2.003000 2.003000 -0.519386 0.000000 0.000000 0.000000 0.000000 0.000000 -0.662271 0.000000 0.000000 10 f/i= 1.213997 THz 7.627769 2PiTHz 40.494585 cm-1 5.020690 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.000000 0.232919 2.003000 0.000000 2.003000 0.000000 0.000000 0.386143 0.000000 2.003000 2.003000 0.000000 0.000000 0.239573 2.003000 2.003000 2.003000 0.000000 0.000000 0.527859 0.000000 0.000000 0.000000 0.000000 0.000000 0.678684 11 f/i= 1.589322 THz 9.986006 2PiTHz 53.014082 cm-1 6.572911 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.365880 0.000000 2.003000 0.000000 2.003000 0.000000 0.035667 0.000000 0.000000 2.003000 2.003000 0.000000 0.131682 0.000000 2.003000 2.003000 2.003000 0.000000 0.669647 0.000000 0.000000 0.000000 0.000000 0.000000 0.631738 0.000000 12 f/i= 5.231244 THz 32.868872 2PiTHz 174.495495 cm-1 21.634692 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.321368 0.000000 0.000000 2.003000 0.000000 2.003000 -0.683471 0.000000 0.000000 0.000000 2.003000 2.003000 -0.452513 0.000000 0.000000 2.003000 2.003000 2.003000 0.427094 0.000000 0.000000 0.000000 0.000000 0.000000 0.205943 0.000000 0.000000 13 f/i= 11.525150 THz 72.414655 2PiTHz 384.437620 cm-1 47.664207 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.000000 0.766389 2.003000 0.000000 2.003000 0.000000 0.000000 0.254010 0.000000 2.003000 2.003000 0.000000 0.000000 0.041048 2.003000 2.003000 2.003000 0.000000 0.000000 -0.587555 0.000000 0.000000 0.000000 0.000000 0.000000 0.034953 14 f/i= 12.506382 THz 78.579915 2PiTHz 417.167986 cm-1 51.722257 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.860329 0.000000 0.000000 2.003000 0.000000 2.003000 -0.063727 0.000000 0.000000 0.000000 2.003000 2.003000 0.320460 0.000000 0.000000 2.003000 2.003000 2.003000 -0.388825 0.000000 0.000000 0.000000 0.000000 0.000000 -0.043508 0.000000 0.000000 15 f/i= 14.030104 THz 88.153744 2PiTHz 467.993886 cm-1 58.023868 meV X Y Z dx dy dz 2.003000 2.003000 0.000000 0.000000 0.785974 0.000000 2.003000 0.000000 2.003000 0.000000 0.407546 0.000000 0.000000 2.003000 2.003000 0.000000 -0.012030 0.000000 2.003000 2.003000 2.003000 0.000000 -0.464468 0.000000 0.000000 0.000000 0.000000 0.000000 0.016629 0.000000 |
木蟲 (著名寫手)

金蟲 (著名寫手)
至尊木蟲 (著名寫手)
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樓主所言有限差分法可能是因為手冊中說"To calculate the Hessian matrix, finite differences are used”,不知道是不是該翻成“有限差分法”。 詳見http://cms.mpi.univie.ac.at/vasp/vasp/IBRION_5_IBRION_6.html |

至尊木蟲 (著名寫手)

至尊木蟲 (著名寫手)

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