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Andrei V Scherbinin
andrei.scherb@gmail.com

> � (default is n=5, except CI or MP2 gradients n=6)

if you use default OPTTOL value, and if you do not experience problems with basis set dependence,
for instance.

Of course, if you decreased OPTTOL (say, ~0.00001) for tighter geometry optimization, then it would
be wise to converge your SCF tighter, say, up to NCONV=7 or so.

Andrei



On Tue Jan 25 '11 4:41pm, Masoud Nahali wrote
---------------------------------------------
>Dear Firefly Users

>I have used "NCONV=4.5" in my input for the SCF convergence. It means that the convergence is reached when the density change between two consecutive SCF cycles is less than 10^(-4.5) or 3*10^(-5).
>
>the lines below is one of my SCF steps :

> ITER EX DEM �TOTAL ENERGY � � �E CHANGE �DENSITY CHANGE � �DIIS ERROR � � �INTEGRALS � SKIPPED
> � � � � �* * * � INITIATING DIIS PROCEDURE � * * *
> � 1 �0 �0 -3654.010061008 -3654.010061008 � 0.027738005 � 0.006150221 � � � � � � -1 � � � �-1
> � 2 �1 �0 -3654.010871171 � �-0.000810163 � 0.023518159 � 0.022479261 � � � � � � -1 � � � �-1
> � 3 �2 �0 -3654.013930379 � �-0.003059209 � 0.008856269 � 0.008333109 � � � � � � -1 � � � �-1
> � 4 �3 �0 -3654.013534182 � � 0.000396198 � 0.005316080 � 0.003565101 � � � � � � -1 � � � �-1
> � 5 �4 �0 -3654.014225050 � �-0.000690868 � 0.001903469 � 0.005148299 � � � � � � -1 � � � �-1
> � 6 �5 �0 -3654.014368343 � �-0.000143293 � 0.000956684 � 0.002133792 � � � � � � -1 � � � �-1
> � 7 �6 �0 -3654.014404861 � �-0.000036518 � 0.000503151 � 0.000987793 � � � � � � -1 � � � �-1
> � 8 �7 �0 -3654.014412598 � �-0.000007738 � 0.000385881 � 0.000328227 � � � � � � -1 � � � �-1

> � � � � �-----------------
> � � � � �DENSITY CONVERGED
> � � � � �-----------------

>As it is clear 0.000385881 > 3*10^(-5) ; so why the density was converged ? Is there another criteria to reach the convergence ?

>Is the "NCONV=4.5" logical when my "OPTTOL" value is 0.0001 ?

>I appreciate your help in advance to understand the convergence criteria better.
>
>
>
> Best Wishes

> Masoud
>--------------
>Masoud Nahali, Sharif University of Technology �