<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Yuri,<br><br>Your finite field _method_ is OK but:<br><br>1. Your applied field is too small. Try f=[0.0001,-0.0001]<br>2. Be sure your geometry (& geometry section) is correct. E.g., CH bondlength in methane is about 1.099 Angstroms but your CH bondlengths are 1.18912*sqrt(3) Angstroms. <br><br>When you are off by less than orders of magnitude, check:<br>3. Methane has 2 independent non-zero hexadecapole moments (Q40, Q43, say). If you are trying to calculate Q40, Check the prefactor. I am _guessing_ there would be a factor of (35/8) to multiply your <zzzz><br><br>My $0.02.<br><br>o.<br><br><br>--- On <b>Wed, 6/9/10, Yurii Vlasov <i><vlasov.yura@gmail.com></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><br>From: Yurii Vlasov <vlasov.yura@gmail.com><br>Subject:
[molpro-user] hexadecapole moment of CH4 using finite-field<br>To: molpro-user@molpro.net<br>Date: Wednesday, June 9, 2010, 6:09 AM<br><br><div id="yiv358645336">Dear Molpro Community,<br><br>I have a problem with the calculation of the hexadecapole moment of CH4 molecule using finite-field method. But I've got the value of Hexadec mom = -2.01067478D+07 ! (It should be ~7 a.u. according to Maroulis, or if to calculate the expectation value). May be I didn't understand correctly the idea of finite field method... <br>
<br>Could anyone help me. I would be very appreciated<br>Thank you in advance, Yurii<br><br><br>***,CH4 hexadecapole<br>memory,20,m<br><br>GTHRESH, oneint=1.d-14, energy=1.d-9, step=1.d-5,<br>twoint=1.d-14, prefac=1.d-14<br>
GTHRESH, coeff=1.0d-5, zero=1.0d-14<br>symmetry,nosym<br><br>geometry={<br> 1 C1,, 0., 0., 0.,<br> 2 H2,, 1.18912 1.18912 1.18912,<br> 3 H3,, -1.18912 -1.18912 1.18912,<br> 4 H4,, -1.18912 1.18912 -1.18912<br>
5 H5,, 1.18912 -1.18912 -1.18912, <br>}<br>basis=avtz<br><br>f=[0.000001,-0.000001]<br>method=[hf]<br>k=0<br>do i=1,#f<br>field,zzzz,f(i)<br>hf <br>e(k)=energy<br>end do<br><br>k=0<br>n=1<br>do m=1,1<br> k=k+1<br>
hexz(m)=(e(k)-e(k+n))/(f(1)-f(2))<br>end do<br><br>table,method,hexz<br>title,hexadecapole (zzzz) result for CH4<br><br><br><br>
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