<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Dear Mateusz,<div class=""><br class=""></div><div class="">The MEASURE_LOCAL_AT function is not at all optimal. This is however the cost of being generic…</div><div class=""><br class=""></div><div class="">For the nearest neighbors correlations you could actually use the MEASURE_LOCAL with a bond operator.</div><div class="">This will measure on all bonds in the lattice definition.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Best,</div><div class="">Michele</div><div class=""><br class=""><div class="">
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant-ligatures: normal; font-variant-position: normal; font-variant-caps: normal; font-variant-numeric: normal; font-variant-alternates: normal; font-variant-east-asian: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">--</div><div class="">ETH Zurich</div><div class=""><span style="text-align: -webkit-auto;" class="">Dr.</span><span style="text-align: -webkit-auto;" class=""> </span>Michele Dolfi</div><div class="">Institute for Theoretical Physics</div><div class="">HIT G 32.4</div><div class="">Wolfgang-Pauli-Str. 27</div><div class="">8093 Zurich</div><div class="">Switzerland</div><div class=""><br class=""></div><div class=""><a href="mailto:dolfim@phys.ethz.ch" class="">dolfim@phys.ethz.ch</a></div><div class=""><a href="http://www.itp.phys.ethz.ch" class="">www.itp.phys.ethz.ch</a></div><div class=""><br class=""></div><div class="">+41 44 633 78 56 phone</div><div class="">+41 44 633 11 15 fax </div></div>
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<br class=""><div><blockquote type="cite" class=""><div class="">On 14 Jan 2017, at 09:05, Mateusz Łącki <<a href="mailto:mateusz.lacki@gmail.com" class="">mateusz.lacki@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Dear All,<br class="">I am trying to compute properties of a quantum ising model in the transverse field. I want to measure local magnetization (both transverse and along the field), and nearest neighbor correlations Sx(i) Sx(i+1) and Sz(i) Sz(i+1) for each two nearest neighbours. Later I plan on adding additional terms, but below I present the minimum model representing the problems.<br class=""><br class="">For longer lattices however over 90% cpu time (tens of minutes, hours) is spent in measurement of the correlation functions. <br class=""><br class="">Am I doing something wrong?<br class=""><br class="">Best,<br class="">Mateusz Łącki<br class=""><br class=""><br class=""><br class=""><br class="">My input file is as follows:<br class=""><br class="">LATTICE="open chain lattice"<br class="">MODEL=“spin"<br class=""><br class="">J=1<br class="">SWEEPS=10<br class="">chkp_each=10<br class="">deleteafteruse=0<br class="">MEASURE_LOCAL[Local magnetization X]=Sx<br class="">MEASURE_LOCAL[Local magnetization Z]=Sz<br class=""><br class="">MEASURE_LOCAL_AT[SzSz] = "Sz:Sz|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “<br class=""><br class="">MEASURE_LOCAL_AT[SpSp] = "Splus:Splus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “<br class=""><br class="">MEASURE_LOCAL_AT[SmSp] = "Sminus:Splus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “<br class=""><br class="">MEASURE_LOCAL_AT[SpSm] = "Splus:Sminus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “<br class=""><br class="">MEASURE_LOCAL_AT[SmSm] = "Sminus:Sminus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) "<br class="">L=128;<br class="">MAXSTATES=200;<br class="">NUMBER_EIGENVALUES=1;<br class=""><br class="">{h=1;}<br class=""><br class=""><br class=""><br class=""><br class="">----<br class="">Comp-phys-alps-users Mailing List for the ALPS Project<br class=""><a href="http://alps.comp-phys.org/" class="">http://alps.comp-phys.org/</a><br class=""><br class="">List info: https://lists.phys.ethz.ch//listinfo/comp-phys-alps-users<br class="">Archive: https://lists.phys.ethz.ch//pipermail/comp-phys-alps-users<br class=""><br class="">Unsubscribe by writing a mail to comp-phys-alps-users-leave@lists.phys.ethz.ch.</div></div></blockquote></div><br class=""></div></body></html>