Hello All,
I've encountered some problems with the use of $fermi in TURBOMOLE V6.0
I want to optimize the structure of some hydrocarbons with DFT (using the pbe functional for instance). For this purpose I use the jobex script with relax or statpt.
Seemingly during the optimization everything works quite alright. When I check the occupation with eiger after the run has finished, I see a negative HOMO-LUMO gap. To cope with this problem I tried to use $fermi with the following parameters
$fermi tmstrt= 25.00 tmend= 25.00 tmfac=1.000 hlcrt=1.0E+00 stop=1.0E-09
.
However, as the result of an ridft run I still don't get a positive HOMO-LUMO gap, even though the occupation is calculated with $fermi until the energy converges. The problem seems to be that after convergence an additional energy calculation step takes place, where $fermi for unknown reasons does not apply any more. Here are the details of the last few steps of my ridft output file:
ITERATION ENERGY 1e-ENERGY 2e-ENERGY NORM[dD(SAO)] TOL
62 -1179.8455826780 -6122.2798253 2670.1641575 0.523D-04 0.225D-12
Exc = -161.191934466 Coul = 2831.35609200
N = 181.99989069
current damping = 1.050
Norm of current diis error: 0.39805E-04
max. resid. norm for Fia-block= 3.340D-06 for orbital 91a
max. resid. fock norm = 3.475D-06 for orbital 91a
irrep a : virtual orbitals shifted by 0.10846
-------------------- FON Calculation ---------------------
Fermi level F = -0.12539
Total number of electrons N = 182.00000
Occupation numbers calculated for T = 25.00000
Current HOMO-LUMO gap = 0.48780E-01
----------------------------------------------------------
ITERATION ENERGY 1e-ENERGY 2e-ENERGY NORM[dD(SAO)] TOL
63 -1179.8455826783 -6122.2798664 2670.1641986 0.326D-04 0.225D-12
Exc = -161.191933054 Coul = 2831.35613170
N = 181.99989069
current damping = 1.100
Norm of current diis error: 0.34798E-04
max. resid. norm for Fia-block= 3.484D-06 for orbital 91a
max. resid. fock norm = 6.557D-06 for orbital 366a
irrep a : virtual orbitals shifted by 0.06828
-------------------- FON Calculation ---------------------
Fermi level F = -0.12539
Total number of electrons N = 182.00000
Occupation numbers calculated for T = 25.00000
Current HOMO-LUMO gap = 0.15104E-01
----------------------------------------------------------
ENERGY CONVERGED !
Overall gridpoints after grid construction = 665045
ITERATION ENERGY 1e-ENERGY 2e-ENERGY NORM[dD(SAO)] TOL
64 -1179.8455516457 -6122.2798324 2670.1641956 0.326D-04 0.790D-12
Exc = -161.191902780 Coul = 2831.35609842
N = 182.00000695
current damping = 1.150
Norm of current diis error: 0.25621E-04
max. resid. norm for Fia-block= 2.367D-06 for orbital 91a
max. resid. fock norm = 2.453D-06 for orbital 91a
End of SCF iterations
convergence criteria satisfied after 64 iterations
Using the eiger script I get the following occupation:
Total energy = -1179.8455516460 H = -32105.2492441 eV
HOMO-LUMO Separation
HOMO: 92. 91 a -0.12635850 H = -3.43839 eV
LUMO: 91. 92 a -0.14829956 H = -4.03544 eV
Gap : -0.02194106 H = -0.59705 eV
!! WARNING: HOMO-LUMO Gap is negativ !!
Number of MOs= 396, Electrons= 182.00, Symmetry: c1
Nr. Orbital Occupation Energy
108. 108 a +0.085909 H = +2.338 eV
107. 107 a +0.084492 H = +2.299 eV
106. 106 a +0.074339 H = +2.023 eV
105. 105 a +0.072635 H = +1.976 eV
104. 104 a +0.065869 H = +1.792 eV
103. 103 a +0.063547 H = +1.729 eV
102. 102 a +0.055610 H = +1.513 eV
101. 101 a +0.053687 H = +1.461 eV
100. 100 a +0.039238 H = +1.068 eV
99. 99 a +0.037697 H = +1.026 eV
98. 98 a +0.001710 H = +0.047 eV
97. 97 a -0.029023 H = -0.790 eV
96. 96 a -0.050084 H = -1.363 eV
95. 95 a -0.057593 H = -1.567 eV
94. 94 a -0.069351 H = -1.887 eV
93. 93 a -0.103417 H = -2.814 eV
92. 91 a 2.000 -0.126358 H = -3.438 eV
91. 92 a -0.148300 H = -4.035 eV
90. 90 a 2.000 -0.216450 H = -5.890 eV
89. 89 a 2.000 -0.221611 H = -6.030 eV
88. 88 a 2.000 -0.223412 H = -6.079 eV
87. 87 a 2.000 -0.241772 H = -6.579 eV
86. 86 a 2.000 -0.245310 H = -6.675 eV
85. 85 a 2.000 -0.253361 H = -6.894 eV
84. 84 a 2.000 -0.268394 H = -7.303 eV
83. 83 a 2.000 -0.293210 H = -7.979 eV
82. 82 a 2.000 -0.298763 H = -8.130 eV
81. 81 a 2.000 -0.303391 H = -8.256 eV
80. 80 a 2.000 -0.310105 H = -8.438 eV
79. 79 a 2.000 -0.332052 H = -9.036 eV
78. 78 a 2.000 -0.334060 H = -9.090 eV
77. 77 a 2.000 -0.334539 H = -9.103 eV
76. 76 a 2.000 -0.349200 H = -9.502 eV
What exactly is happening here? And as a general question: Why is this last energy step calculated, after the energy is converged?
Thanks very much for your help,
Andi